ttering　harsh　cries；　such　attitudes　and　utterances　after　a　time　becoming　through　habit　instinctive。　In　this　manner　actions　performed　by　the　contraction　of　voluntary　muscles　might　have　been　combined　for　the　same　special　purpose　with　those　effected　by　involuntary　muscles。　It　is　even　possible　that　animals；　when　excited　and　dimly　conscious　of　some　change　in　the　state　of　their　hair；　might　act　on　it　by　repeated　exertions　of　their　attention　and　will；　for　we　have　reason　to　believe　that　the　will　is　able　to　influence　in　an　obscure　manner　the　action　of　some　unstriped　or　involuntary　muscles；　as　in　the　period　of　the　peristaltic　movements　of　the　intestines；　and　in　the　contraction　of　the　bladder。　Nor　must　we　overlook　the　part　which　variation　and　natural　selection　may　have　played；　for　the　males　which　succeeded　in　making　themselves　appear　the　most　terrible　to　their　rivals；　or　to　their　other　enemies；　if　not　of　overwhelming　power；　will　on　an　average　have　left　more　offspring　to　inherit　their　characteristic　qualities；　whatever　these　may　be　and　however　first　acquired；　than　have　other　males。
  ＇20＇　‘Lehrbuch　der　Histologie；'　1857；　s。　　82。
  _The　inflation　of　the　body；　and　other　means　of　exciting　fear　in　an　enemy_。Certain　Amphibians　and　Reptiles；　which　either　have　no　spines　to　erect；　or　no　muscles　by　which　they　can　be　erected；　enlarge　themselves　when　alarmed　or　angry　by　inhaling　air。　This　is　well　known　to　be　the　case　with　toads　and　frogs。　The　latter　animal　is　made；　in　AEsop's　fable　of　the　‘Ox　and　the　Frog；'　to　blow　itself　up　from　vanity　and　envy　until　it　burst。　This　action　must　have　been　observed　during　the　most　ancient　times；　as；　according　to　Mr。　Hensleigh　Wedgwood；＇21＇　the　word　_toad_　expresses　in　all　the　languages　of　Europe　the　habit　of　swelling。　　It　has　been　observed　with　some　of　the　exotic　species　in　the　Zoological　Gardens；　and　Dr。　Gunther　believes　that　it　is　general　throughout　the　group。　Judging　from　analogy；　the　primary　purpose　probably　was　to　make　the　body　appear　as　large　and　frightful　as　possible　to　an　enemy；　but　another；　and　perhaps　more　important　secondary　advantage　is　thus　gained。　When　frogs　are　seized　by　snakes；　which　are　their　chief　enemies；　they　enlarge　themselves　wonderfully；　so　that　if　the　snake　be　of　small　size；　as　Dr。　Gunther　informs　me；　it　cannot　swallow　the　frog；　which　thus　escapes　being　devoured。
  ＇21＇　‘Dictionary　of　English　Etymology；'　p。　　403。
  Chameleons　and　some　other　lizards　inflate　themselves　when　angry。　Thus　a　species　inhabiting　Oregon；　the　_Tapaya　Douglasii_；　is　slow　in　its　movements　and　does　not　bite；　but　has　a　ferocious　aspect；　〃when　irritated　it　springs　in　a　most　threatening　manner　at　anything　pointed　at　it；　at　the　same　time　opening　its　mouth　wide　and　hissing　audibly；　after　which　it　inflates　its　body；　and　shows　other　marks　of　anger。〃＇22＇
  Several　kinds　of　snakes　likewise　inflate　themselves　when　irritated。　The　puff…adder　（_Clotho　arietans_）　is　remarkable　in　this　respect；　but　I　believe；　after　carefully　watching　these　animals；　that　they　do　not　act　thus　for　the　sake　of　increasing　their　apparent　bulk；　but　simply　for　inhaling　a　large　supply　of　air；　so　as　to　produce　their　surprisingly　loud；　harsh；　and　prolonged　hissing　sound。　The　Cobras…de…capello；　when　irritated；　enlarge　themselves　a　little；　and　hiss　moderately；　but；　at　the　same　time　they　lift　their　heads　aloft；　and　dilate　by　means　of　their　elongated　anterior　ribs；　the　skin　on　each　side　of　the　neck　into　a　large　flat　disk；the　so…called　hood。　With　their　widely　opened　mouths；　they　then　assume　a　terrific　aspect。　The　benefit　thus　derived　ought　to　be　considerable；　in　order　to　compensate　for　the　somewhat　lessened　rapidity　（though　this　is　still　great）　with　which；　when　dilated；　they　can　strike　at　their　enemies　or　prey；　on　the　same　principle　that　a　broad；　thin　piece　of　wood　cannot　be　moved　through　the　air　so　quickly　as　a　small　round　stick。　An　innocuous　snake；　the　_Trovidonotus　macrophthalmus_；　an　inhabitant　of　India；　likewise　dilates　its　neck　when　irritated；　and　consequently　is　often　mistaken　for　its　compatriot；　the　deadly　Cobra。＇23＇　This　resemblance　perhaps　serves　as　some　protection　to　the　Tropidonotus。
  ＇21＇　See　the　account　of　the　habits　of　this　animal　by　Dr；　Cooper；　as　quoted　in　‘Nature；'　April　27；　1871；　p。　　512。
  ＇22＇　Dr。　Gunther；　‘Reptiles　of　British　India；'　p。　　262。
  Another　innocuous　species；　the　Dasypeltis　of　South　Africa；　blows　itself　out；　distends　its　neck；　hisses　and　darts　at　an　intruder。＇24＇　Many　other　snakes　hiss　under　similar　circumstances。　They　also　rapidly　vibrate　their　protruded　tongues；　and　this　may　aid　in　increasing　their　terrific　appearance。
  Snakes　possess　other　means　of　producing　sounds　besides　hissing。　Many　years　ago　I　observed　in　South　America　that　a　venomous　Trigonocephalus；　when　disturbed；　rapidly　vibrated　the　end　of　its　tail；　which　striking　against　the　dry　grass　and　twigs　produced　a　rattling　noise　that　could　be　distinctly　heard　at　the　distance　of　six　feet。＇25＇　The　deadly　and　fierce　_Echis　carinata_　of　India　produces　〃a　curious　prolonged；　almost　hissing　sound　in　a　very　different　manner；　namely　by　rubbing　〃the　sides　of　the　folds　of　its　body　against　each　other；〃　whilst　the　head　remains　in　almost　the　same　position。　The　scales　on　the　sides；　and　not　on　other　parts　of　the　body；　are　strongly　keeled；　with　the　keels　toothed　like　a　saw；　and　as　the　coiled…up　animal　rubs　its　sides　together；　these　grate　against　each　other。＇26＇　Lastly；　we　have　the　well…known　case　of　the　Rattle…snake。　He　who　has　merely　shaken　the　rattle　of　a　dead　snake；　can　form　no　just　idea　of　the　sound　produced　by　the　living　animal。　Professor　Shaler　states　that　it　is　indistinguishable　from　that　made　by　the　male　of　a　large　Cicada　（an　Homopterous　insect）；　which　inhabits　the　same　district。＇27＇　In　the　Zoological　Gardens；　when　the　rattle…snakes　and　puff…adders　were　greatly　excited　at　the　same　time；　I　was　much　struck　at　the　similarity　of　the　sound　produced　by　them；　and　although　that　made　by　the　rattle…snake　is　louder　and　shriller　than　the　hissing　of　the　puff…adder；　yet　when　standing　at　some　yards　distance　I　could　scarcely　distinguish　the　two。　For　whatever　purpose　the　sound　is　produced　by　the　one　species；　I　can　hardly　doubt　that　it　serves　for　the　same　purpose　in　the　other　species；　and　I　conclude　from　the　threatening　gestures　made　at　the　same　time　by　many　snakes；　that　their　hissing；the　rattling　of　the　rattle…snake　and　of　the　tail　of　the　Trigonocephalus；the　grating　of　the　scales　of　the　Echis；and　the　dilatation　of　the　hood　of　the　Cobra；　all　subserve　the　same　end；　namely；　to　make　them　appear　terrible　to　their　enemies。＇28＇
  ＇24＇　Mr。　J。　Mansel　Weale；　‘Nature；'　April　27；　1871；　p。　　508。
  ＇25＇　‘Journal　of　Researches　during　the　Voyage　of　the　〃Beagle；〃　'　1845；　p。　　96。　　I　have　compared　the　rattling　thus　produced　with　that　of　the　Rattle…snake。
  ＇26＇　See　the　account　by　Dr。　Anderson；　Proc。　　Zool。　　Soc。　　1871；　p。　　196。
  ＇27＇　The　‘American　Naturalist；'　Jan。　1872；　p。　　32。　　I　regret　that　I　cannot　follow　Prof。　Shaler　in　believing　that　the　rattle　has　been　developed；　by　the　aid　of　natural　selection；　for　the　sake　of　producing　sounds　which　deceive　and　attract　birds；　so　that　they　may　serve　as　prey　to　the　snake。
  It　seems　at　first　a　probable　conclusion　that　venomous　snakes；　such　as　the　foregoing；　from　being　already　so　well　defended　by　their　poison…fangs；　would　never　be　attacked　by　any　enemy；　and　consequently　would　have
  ｛note　＇27＇　continued｝　I　do　not；　however；　wish　to　doubt　that　the　sounds　may　occasionally　subserve　this　end。　But　the　conclusion　at　which　I　have　arrived；　viz。　　that　the　rattling　serves　as　a　warning　to　would…be　devourers；　appears　to　me　much　more　probable；　as　it　connects　together　various　classes　of　facts。　If　this　snake　had　acquired　its　rattle　and　the　habit　of　rattling；　for　the　sake　of　attracting　prey；　it　does　not　seem　probable　that　it　would　have　invariably　used　its　instrument　when　angered　or　disturbed。　Prof。　Shaler　takes　nearly　the　same　view　as　I　do　of　the　manner　of　development　of　the　rattle；　and　I　have　always　held　this　opinion　since　observing　the　Trigonocephalus　in　South　America。
  ＇28＇　From　the　accounts　lately　collected；　and　given　in　the　‘Journal　of　the　Linnean　Society；'　by　Airs。　　Barber；　on　the　habits　of　the　snakes　of　South　Africa；　and　from　the　accounts　published　by　several　writers；　for　instance　by　Lawson；　of　the　rattle…snake　in　North　America；it　does　not　seem　improbable　that　the　terrific　appearance　of　snakes　and　the　sounds　produced　by　them；　may　likewise　serve　in　procuring　prey；　by　paralysing；　or　as　it　is　sometimes　called　fascinating；　the　smaller　animals。　no　need　to　excite　additional　terror。　　But　this　is　far　from　being　the　case；　for　they　are　largely　preyed　on　in　all　quarters　of　the　world　by　many　animals。　It　is　well　known　that　pigs　are　employed　in　the　United　States　to　clear　districts　infested　with　rattle…snakes；　which　they　do　most　effectually。＇29＇　In　England　the　hedgehog　attacks　and　devours　the　viper。　In　India；　as　I　hear　from　Dr。　Jerdon；　several　kinds　of　hawks；　and　at　least　one　mammal；　the　Herpestes；　kill　cobras　and　other　venomous　species；＇30＇　and　so　it　is　in　South　Africa。　　Therefore　it　is　by　no　means　improbable　that　any　sounds　or　signs　by　which　the　venomous　species　could　instantly　make　themselves　recognized　as　dangerous；　would　be　of　more　service　to　them　than　to　the　innocuous　species　which　would　no