1886.] 44d [Cope. 



Urodela in all of the characters given, except in the exclusion of the 

 frontals from the supraorbital border, and in the membranous character- 

 istic of the internal wall of the vestibule. The Amphiumidae differ from 

 other Urodela in the presence of a large ethmoid bone (the one referred 

 to as ? vomer in the diagnosis above quoted), in the presence of temporal 

 ridges, and of two anteriorly directed hypapophyses of the precaudal ver- 

 tebra?. 



It is interesting to notice that three of the four characters just cited are 

 shared by the Cseciliidse. The presence of the ethmoid is of especial im- 

 portance, as it is an element constantly wanting in the Urodela. I have 

 not found it in Desmognathus, Anaides, Spelerpes, Amblystoma, Sala- 

 mandra, nor Protonopsis ; nor is it present in Necturus or in Siren. It is, 

 on the contrary, always present in Cseciliidae* (see Plate v, E). The 

 double anterior hypapophyses are otherwise confined to the same family. 



The Cteciliidse are generally regarded as representing a distinct order, 

 which bears the names Apoda, or Gymnophiona. The definition given to 

 this order by Mr. Boulengerf is : "No limbs; tail rudimentary. Males 

 with an intromittent copulatory organ. Adapted for burrowing." Of 

 these definitions none is of ordinal value. The tail in some species is dis- 

 tinct. The intromittant copulatory organ in Dermophis mexicanus, Gym- 

 nopis proxi?nus, and Herpele oclirocephala, is not an especial organ, but is 

 merely the everted cloaca. The hard papillae observed by GuntherJ in the 

 IchthyopMs glutinosus are wanting in the above species. The protrusion 

 of the cloaca is effected by two especial muscles, which are wanting in 

 Amphiumida3. As to limbs, their extremely rudimentary character in 

 Amphiuma is well known. To regard their condition as indicating ordi- 

 nal separation from the Cteciliidse is not in accordance with our practice 

 in similar cases in the Reptilia, as in the order Lacertilia. The characters 

 of these parts and their supporting arches not having been heretofore 

 given, I describe them below. 



I have endeavored to sustain the order Gymnophiona by the character 

 of the fusion of the nasal and premaxillary bones found in the majority 

 of the genera. § But Stannius|| shows that these bones are distinct in 

 Ichthyophis. Huxley states (Anatomy of Vertebrate Animals, p. 155) 

 that in Icht7iyop7iis glutinosus a distinct bone nearly encircles the orbit. 

 This he compares to the supra and postorbital bones found in the Stego- 

 cephali. But in Chthonerpeton, Ctecilia. Dermophis and other genera, 

 this bone forms part of the maxillary, so that it is not characteristic of the 

 family, and may not be homologous with the bones which occupy the same 

 position in Stegocephali. Wiedersheim calls it maxillary. 



With these facts in view I have united^f the Creciliidse with the Urodela, 



*See Wiedersheim, Anatomie der Gymnophionen, Jena, 1879. 

 t Catalogue of the British Museum, 1882, p. 88. 

 X Reptiles of British India (Roy. Society), p. 411. 

 \ American Naturalist, 1884, p. 26. 



II Zootomie der Amphibien, 1856, p. 11. 



\ American Naturalist, 1885, p. 211, note. 



