AND AYES OF NORTH AMERICA. 21 



series of caudal vertebra; is quite short, and the ribs are short and but little curved. In 

 Molgophis the tail has been like that of an elongate serpent, and the ribs are a> well 

 developed as those of many reptiles. 



Though no limbs or arches can be certainly found, a rather quadrate, parallelogrammic 

 piece, about as long as the diameter of a vertebra, may be found. This is however verj 

 doubtful. 



The characters of the genus are: a long serpentine body, without dermal armature, so 

 far as discoverable; the vertebra? large and broad with very prominent zygapophyses and 

 moderate neural spine, those of the caudals without narrowed bases (and grooved or 

 serrate edges, most probably). Limbs and cranium unknown. 



This genus differs from Urocordylus in its caudal vertebra?, and from Ophiderpeton in 

 its dorsals: the latter in their zygapophyses projecting laterally resemble those of Amphi- 

 uma. It differs from OEstocephalus in the absence of ventral dermal bands and in the 

 longer body, without indication of limbs. The size of the vertebra? would indicate a body 

 of the size of a rattlesnake, (C. horrida,) and therefore too large for the species named 

 Brachydectes neicberryi. 



The ribs are long, and though the head is not bifurcate, there appear to be both 

 tubercle and head on the dilated extremity. They show themselves where crushed to 

 have a large median vacuity. 



MOLGOPHIS MACRTTRTJS, Cope. 



The neural arches viewed from above have a posterior V-shaped outline, from the fact that the broad zygapo- 

 physes meet on the median line, and spread out distally over the broad anterior ones adjoining. The latter appear to 

 be somewhat concave, and to border the former exteriorly as well as inferiorly. The base of the neural spine extends 

 to the posterior emargiuation, but not quite to the anterior. The breadth of the dorsal vertebra above is equal from 

 the emargination behind to the anterior margin of the anterior zygapophysis. 



The caudal series must have been very long, as there is very little diminution in the size of the vertebrae through- 

 out the series preserved. They present much the same form as the dorsals, but are more contracted medially, and 

 the zygapophyses have a more transverse direction. There may indeed be a diapophysial element beneath these, but 

 the two cannot be distinguished if so. They are connected by longitudial impressions, indicating the existence of 

 the tendinous bands in the longitudinal muscles seen in Amphiunua, or the osseous spicules in the same situation in 

 birds. The neural spines indicated by their narrow bases, occupied the length of the neural arch, and remind one of 

 Ampliiuma. 



The ribs are long for a Batraehian, but shorter than in a reptile. They are well curved, chiefly near the proximal 

 extremity. The longest I can find measured by a chord, equals two vertebrae and two-fifths. Three vertebra? 

 measured along the median line above equal eleven lines ; one of these is 3.6 lines in width above : width of a :' 

 posterior caudal 3 1. 



This animal has been like Amphiuma a snake-like Batraehian, but probably of even more elongate form. How 

 near its affinities to this genus may be, cannot be ascertained, owing to want of important parts of the skeleton, but 

 it differs in the important feature of the large, well developed ribs. 



AMERT. PHILOSO. SOC. — VOL. XIV. 6 



