THE EATRACHIA OF NORTH AMERICA. 37 



Of this family but two existing geuera are known, altliough it is 

 qaite probable that a third has left remains in the Miocene lacustrine 

 beds at Oeningen, in Germany, which is kuown under the name of Au- 

 drias. The existing genera differ as follows : 



IJi'Jincliial fissure present Crypto'brancliKS- 



No branchial fissure Megalahatracliiis. 



The Megalobatrachus maximus is found in Japan and eastern Asia as 

 far southwest as eastern Thibet. I^ exceeds in dimensions the species 

 of Cryptobranchus, which are exclusively North American, but has a 

 great general resemblance to them. 



The nearest ap])roach to this family among other Urodela is made by 

 the family of Amblystomida?.. The structural diflerences are, however, 

 import.ant. 



CRYPTOBRANCHUS Leuckart. 



Isis, 1821, p. 2G0. Boulenger, Catal. Batr. Grail. Britr. Mus., 1882, p. 81. 

 Ahranclins. Harlan, Annals, Lyceum Nat. Hist. New York, 1825, r, p. 221. 

 ilfeH02)o?Ha. Harlan, /. c, p. 270; Tschudi, Batr., 90; Dum. Bibr., Eop. G6u., ix, p.205. 

 Sulamandrops. Wagl., Nat. Syst. Anipbib., 1830, p. 209. 

 Enrijaa. Rafinesqne (teste Baird), Atlantic Journal, 1832, p. 121. 

 Frotoxcpsis. "Barton", Gray, Catal. Batr. Grad. Brit. Mus., ed. i, p. 53. 



In this genus the vomerine teeth form a regularly arched series, con- 

 centric with the maxillary seiies. The tongue is but little free, and 

 that only round tlie edges. The columella of the stapes is cartilaginous, 

 and is connected by a close articular contact with the quadrate carti- 

 lage and with the under side of the squamosal bone. The ccratohyal 

 is connected by a ligament with the posterior side of the quadrate, with 

 the intervention of an oval cartilage, which has the position of the sty- 

 loliyal bone of fishes. The posterior extremity of the ceratohyal is not 

 incurved, and is free from the skull. (Plate 48, fig. 3.) 



The hyoid apparatus is quite characteristic. They have been already 

 described so far as they define the suborder Trematodera. They re 

 semblo the Pseudosauria in having two ceratobrauchials, but differ from 

 them and resemble the Amphiumoidea in having no first epibrancliial. 

 This element may, however, be confluent with the first ceratobranchial, 

 but no suture appears in very young specimens. The ceratohyals are 

 divided transversely and the hypohyals are large. They are not in 

 contact with each other or with the first basibrauchial, as in other or- 

 ders and suborders, but are separated by a pair of transverse elements, 

 which are probably true basihyals. The first basibrauchial appears to 

 be interrupted at its middle, the janterior part remaining attached to 

 the basihyals. No second basibrauchial. 



A broad cartilaginous plate rises from the basibrauchial and supports 

 the tongue. It resembles a good deal the otoglossal cartilage of the 

 AmblystomidfB, with which it is probably homologous.* The second, 

 *This snffs;estioii 1 owe to Dr. Gait. 



