Cope.] 444 [Feb. 5, 



a proposition which I now fully believe to be sustained by the evidence. 

 The Cmciliidce is a family of Urodela, connected with the typical forms 

 through the AmphiumicUe. 



Wiedersheim (1. c. p. 95) has attempted to trace the ancestry of the 

 Cscciliidae to the Stegocephali of the Carboniferous period, from which 

 he supposes them to have arisen by a process of degeneration. He 

 remarks that in order to demonstrate this proposition it is only necessary 

 to discover a type with rudirnental limbs which shall connect the two. 



That the Cseciliidae is a type which has resulted from a degeneration, I 

 have also proposed,* but I have derived them from the Urodela rather than 

 from the Stegocephali direct. They have, like Amphiuma, essentially the 

 same cranial structure as the Urodela, which is widely different from that 

 of the Stegocephali, in the absence of the intercalare, supratemporal and 

 postorbital bones. And these characters are fully maintained in various 

 genera of Stegocephali which have rudirnental limbs. Amphiuma then is 

 the annectant type with rudirnental limbs, which Dr. Wiedersheim sought 

 for. The circumstance that his eyes were turned towards the Stegocephali 

 indisposed him to recognize this fact. 



The only portion of the shoulder girdle of this genus which is ossified is 

 the scapula. The coracoid cartilages of opposite sides are distinct from 

 each other, and there is a production of the prrccoracoid region. The 

 humerus is truncate at both extremities, making its articulations with 

 cartilage only. The carpus is undivided cartilage. The osseous ilium is 

 quite short and slender ; it has a long superior cartilaginous portion, 

 which is attached to an equally long cartilaginous sacral rib. The infe- 

 rior element is an undivided plate, which is wider than long, and presents 

 an obtuse angle anteriorly. The posterior portion of each is occupied by 

 a round discoid ossification, which forms the posterior border, but does 

 not reach either the acetabulum or its fellow. The femur is rather long 

 and has a distinct trochanter, but no head nor condyles. The articula- 

 tions are cartilaginous, as is the tarsus, which is also undivided. The 

 tibia and fibula are about one-sixth the length of the femur, and the fibula 

 is a little shorter and more slender than the tibia. The phalanges in both 

 feet are well ossified. 



The general characters of these parts are described in Stannius' Hand- 

 buch der Zootomie.f but only as included in the definitions of the order 

 to which Amphiuma is referred. 



Plate VI. 



Amphiuma means Gard. One-third natural size. Original. From 

 Georgia. 

 Fig. 1, skull, left side. 

 Fig. 2, do. from above. 



♦American Naturalist, 1885, p. 244. 

 t Rostock, 1856. 



