22 BULLETIN 3i, UNITED STATES NATIONAL MUSEUM, 



sufficieutly well preserve. 1 to allow of a positive determination. This is 

 the Hykcobatrachus croyii of Dollo.* It differs from any of the known 

 genera of tlie order in having five digits on all the feet. 



There is but one existing family of Proteida, which is defined as fol- 

 lows : 



PROTEIDA. 



Ko median sternal elements. Vertebme amphicoelous. Carpus and 

 tarsus cartilaginous. Inner wall of vestibule osseous. Nasalia want- 

 ing. Teelh on all the usual bones except the luaxillaries, which are 

 wanting. The second ceratobranchial is present, as in Urodela gen- 

 erally. Stapes directly connected with the suspensorium. 



Of this family but two genera are known. They are the following : 



External brancliiine; digits 4-4 ; eye.s exposed Nectar Hf<. 



External branchiae.; digits, 3-2; eyes bidden. rrolciis. 



Of these Necturus is North American and Proteus is European. The 

 latter is represented by three or four species, which live in subterrauean 

 waters in the southern parts of Austria. 



These genera differ somewhat in the hyoid apparatus. The hypo- 

 hyal is present in Kecturus, but is, according to Wiedersheim, wanting 

 in Proteus. In the former the second ceratobranchial is much smaller 

 than in the latter, and is not connected with the basibranchials. 



The connections between the inferior arches and the skull are inter- 

 esting. In Necturus the columella is osseous and is bent abruptly for- 

 wards, and articulates with a short posterior process of the squamosal 

 bone. The ceratohyal is free from the skull, but is connected with it 

 by the two ligaments, the hyosuspensorial to the middle of the quadrate, 

 and the maudibulohyoid, to the angle of the mandible. (Plate 48, fig. 

 1.) In Proteus (Fig. 2) the arraugemeut is similar, except that the 

 processes of the stapes and squamosal do not meet, but are connected 

 by a strong ligament. 



The intermedium of the carpus and of the tarsus is continent with 

 the adjacent external element, the ulnare and the flbulare. There are 

 three carpalia and three tarsalia, the internal on the inner side of the 

 carpus and tarsus. The carpus and tarsus arc thus very much alike. 

 (Plate 45, fig. 2.) 



The procoracoid cartilages are distinguished from the coracoids, but 

 are continuous at the point of junction with thoai. Tliey are much 

 produced forwards in Necturus. The coracoids meet on the middle line. 

 Ko sternum. The ilium is the only ossified part of the pelvis. It is con- 

 nected with the single sacral vertebra by a true rib, w^hich is rather larger 

 than the others. The inferior elements of the pelvis are continuous car- 

 tilage. Ill Necfcurus the ischiadic portion is subquadrabe, while the 

 public portion forms a triangle, well produced forwards to an acute- 

 angled apex. Femur with a trochanter in Kecturus. 



* Bulletin du Mus6e Eoyal du Belgiqne, 1885, p. 85. 



