THE 13ATRACIIIA OP NORTH AMERICA, 



125 



Or thus : 









Two PREMAXILLARIES. 



Digits 4-5, 

 a. Distinct. 

 Tongue free. 



One ] 



Premaxillaky, 



GiirinopMlus. 



Tongue attached. 





Spelerpes. 



Plethodon. 







Stereochilus. 



' 



aa. United. 







Geotriton. 



Digits 4-4. 





CEdipus. 



HeniidactyUum. 







anculiis. 

 Bairaclioseps. 



Some other characters found iu this fanily are those of low develop- 

 ment and approximations to the larval condition. Thus three of the spe- 

 cies exhibit at times a subnareal cirrhus, which occurs in some of the 

 Coecilid.'e, and Xenopus among Salientia. It is the persistence of that 

 long subocular tentacle characteristic of the early larval stage of Uro- 

 dela generally (see Plate 16), and of a later larval stage of Xenopus 

 {vid. Wyman a7id Gray), where they resemble the appendages of the 

 Silurid?e. They have been called crochets by Eusconi, and homologized 

 with the cylindric cephalic processes of the larval Eana, with what cor- 

 rectness remains to be proven by observations on other types. 



Eschscholtz correctly represents Batraclioseps attenuatus as without 

 prefontals. An elongate process of the frontal occupies only part of its 

 place, forming no suture with the maxillary. This is quite different from 

 Demoguathus, where the orbit is completed by the union of frontal and 

 maxillary. In Mancultis quadridigitatiis the prefrontal occupies this 

 depression as an elongate vertical scale. 



In Spelerpes ruder the quadratum presents a small internal anterior 

 ala, Avhich has a superficial resemblance to a pterygoid. In this species 

 there is apparently an azygus bone behind the premaxillaries. This is, 

 however, only the exposed extremity of their united spines, which are 

 nearly or quite isolated by the approximation of the anterior parts of 

 the nasale. It does not occur in the Gyr'mopMlus porpliyriticus. 



BATEACHOSEPS Bonap. 



Fauna Italica ; Gray, Cat. Brit. Mus., 1850, 42 ; Cope, Proceed. Ac. Phila., 

 1869, p. 98; Strancli, Salam., p. 84; Boulenger, pt. Cat. Brit. Mus., 

 ed. II, 1882, p. 52. 



Tongue adherent anteriorly. Digits 4, 4; a large parietal fontanelle. 

 Premaxillary single, pierced by a fontanelle. 



This genus embraces the forms w'hich may be considered the lowest 

 in the family. It differs from Hemidactylium as Thorius does from 

 Spelerpes, i. e., in the nonossilication of the parietal bones. This low 

 grade of development is here seen in the extremities also, which are 



