AND AYES OF NORTH AMERICA. 



21 



scries of caudal vertebras is quite short, and the ribs arc short and bul little curved. In 

 Molgophis the tail lias been like thai of an elongate serpent, and the ribs are as 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 very 

 doubtful. 



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

 far as discoverable; the vertebras 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 (litters from [Jrocordylus in its caudal vertebra?, and from Ophiderpetou in 

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

 iiiiiii. It ditt'ers from (Kstocephahis 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, (('. horrida,) and therefore too large for the species named 

 Brachydectes newberryi. 



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 MACRURUS, Cope. 



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

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

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

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



I t'e e rgination behind to the anterior margin of the anterior zygapophysis. 



Tin! caudal series must have been very long, as there is very little diminution in the size of the vertebras 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 lie a diapophysial element beneath these, but 

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

 Hie tendinous bands in the longitudinal muscles seen in Amphiunna, or tin' osseous spicules in the same situation ill 

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

 Amphiuma. 



The ribs are Long lor a, l!at laehian, bill, shorter than in a. reptile. Tliev are well curved, chielly near the proximal 

 extremity. The longest I can And measured by a chord, equals two vertebras and two-fifths. Three vertebrse 

 measured along the median line above equal eleven lines ; one of these is 3.6 linos in width above ; widtli of a (?) 

 posterior caudal D 1. 



This animal has been like Amphiuma a snake-like Batraehian, bid; probably of oven more elongate form. How 

 near its affinities to this g( a may lie, cannot be ascertained, owing to want of important parts of the skeleton, but 



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



AMERT, PHILOSO. SOC— VOL. XIV. 6 



