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322 BULLETIN 31, UNITED STATES NATIONAL iMUSEUM. 



The natural genera are as follows : 



I. No teeth on tlio i»iiiiisiibcuoiil boue. 



1. Pupil horizontiil. 



a A fiontopark'tal (biitaiallc ; Hliinr)icl not ossilied aViove. 



Xi„.Kfire Tlwroiia Cope. 



aa. A liontoparii'tal ionlanelle; ctlinioid coiiipUtiil. 



Toes five, or ueaily (so ; <li{;ital dilatations very small; safiuin little 



dil'lted (hoiiiiiliilii" I5aird. 



Toes fully webbed; digital dilatations minute : saeiuin little dilated. 



I, lis \). \ 15. 



Toes webbed; digital disks and sacral diapojdiyses nnu-e dilated ; jm.IIcx 

 consisting of one or more sliort conceab'tl i)balauges; pal|Mbra trans 



parent "nl" ''••i"- 



Like llyla, but the <lorsal derm introverted forwards, forming a sae. 



XolDln nut 1). A 1). 



Like llyla, but pidlex consisting of phalanges (used into a enived >olid 



exsertildo spine: iialpebra transparent /////im7»"/-( \Vmi;1. 



Like llyi)siboas, but paliiebrareticidale with libers CnnlnxiopK^ ('o|m\ 



Like llyla, but vonieriuo teeth wanting IlijliUu If. iV L. 



aa. No frontoparietal fontauelle. 



Derm of the head frei^ ; no post frontal (nocess Si!il(ii>ix Cope. 



Derm of the head free: a postfnmtal juocess Siiiilisin Cope. 



Derm of front free: bones exostosed (Inh(initlialii,t Til/,. 



Derm »d' the head inv.dved in the ossilication ; no dermal .sae. 



Irtirhiiitiihiilus 'I'-eb. 



Derm (d' bead involved in the ossilication; a doisal sac of the int roverlid 

 .skin Djiintlwililjilnix ( ii lir. 



2. Pupil vertical. 



fi. No frontoparietal fontaiudle. 



Tongue scarcely free behind; no digits opposalde; cranial ossilication 



involving lie rm XjirHiiuiiilis I Ion I. 



/3;i. Frontoiiarietal fontunelle present. 



Tongue extensively tree liehind ; sternum <leeply cniarginate; digits not 



oplio.sed when at rest : cranial skin IVee hjiiliii liiiis Cope. 



Tongut? extensively IVee; internal digits opposable, more or Ie>s fni' ; 



sternum entire; cranial skin free riii/lhiiinriiiKi U'agl 



IL Teeth on the ]iaras[ihenoid bom-. 



Pupil horizontal; vomeriiu^ teelh; (;ranial <lertn involved in ossilicit ion 



of skull ; labial biu'ders produced liimjli ii<t Cope. 



VcMueriue teelli; toes webbed; derm ><{' head involved in ossifiiat ion ; 

 labial border produced ; pupil vert ical 'I'liiniiiii ( ope. 



Ill the series 1-2 to rh.vlloiiiediisa a litial «liiiiiiititi<>ii of paliiiatioii 

 aceoiiipaiiies contiiitied .si/.e of the Wi^ital |):ih'tte.s an<l iiicreasi> in th*' 

 length and lueadth of tiic ethmoid and diiiiiiititioii of the fnnitopaiir 

 talis, whieh featiirt'.s, liowever, aiv its iiiaiked in lli/la iialinala ;i.s in 

 these sueeeediiig types; th«'.v eari'.v to its fiiHest (h'v«'iopiii(Mit the cra- 

 nial peculiiirities of the family, and adtl otiicr f«'atiii«'s iK'foic incti 

 tioned; they iiiiiabit the eontineiital siiluegion of the Ncotiopicid. 

 The other nmin series (1-1) leads, liist, to a ftiMcr development (if the 

 frontoparietals, then to an extension of tlie prefiontals, tind litially to 

 covering of the cranium with " dermo-o.ssili(!atioii,"on the one iiiind with 

 the sni)eraddition of a dorstil dermal sa(^, on the other witiiotit it. 'J'his 

 extreme linds itsgretitest expiuision in tlie West Indian siibregiou. .\ 



