NATURAL SCIENCES OF PHILADELPHIA. 217 



continued further forward on one side than the other. These linear scales 

 were arranged as in other genera, in lines which converge forwards to the me- 

 dian line. They are somewhat obscured in the specimen, but it can be de- 

 termined that they are continuous on the median Hue. Whether this is the 

 posterior or anterior portion of the body cannot positively be determined from 

 the specimen ; it is, however, most likely the posterior, for near the posterior 

 portion of the striate surfiice a weak j)air of limbs is given off on each side. On 

 the right, a moderately stout ? femur is followed by a broken tibia and fibula, 

 and by five slender, closely appressed metatarsals. The last are about two- 

 fifths as long as the space between them and the femur; beyond them a few 

 slender phalanges are moderately distinctly defined. The tibia is more distinct 

 on the le'ft, but no tarsus or phalanges ; some of the metatarsals are preserved 

 here also. Length of limb to end of metatarsals equal to five vertebraj in juxta- 

 position, measured along the edges of the neural spines. The limb has been 

 slender, especially the hand. 



The above specimen enables me to assign, as the ventral armature of this 

 species, a closely packed series of V-shaped grooves, which lie in connection 

 with an obscure vertebral column, on the block containing one of the typical 

 specimens of this species. Tliey are not continuous with any of the series ex- 

 hibited on other parts of the block ; some of these at least are the doublings of 

 the slender animal, and this ventral portion has been displaced. The grooves 

 are perhaps the impressions of hannapophysial rods, vastly more numerous, 

 however, than the number of vertebra; ; perhaps they are rather the dermal 

 armature. Huxley figures a portion of this as on the block with Urocordylus 

 wan desfordii , but does not refer it to its precise relation to the animal, 

 A few well-developed ribs are preserved with this portion, — the only ones I 

 can refer to this species. The vertebra' are partly enclosed in matrix, partly 

 impressions. The neural spines, though expanded antero-posteriorly, are less 

 elevated than in the caudal region, and have left no traces of their character- 

 istic ribs or serration. 



The number of spines in the type specimens is six in a half-inch ; in the 

 smallest, just described, ten in the same distance. The height of the spine in 

 the former is 1-15 lines. 



As the characters of this species are most determinable, I regard it as the 

 type of the genus Sauropleura. 



Sauropleura kemex Cope. 



This species is larger than the S. pectinata, and about equal to the Uro- 

 cordylus wandesfordii Huxl. The caudal spines differ from both in the 

 greater attenuation of the haemal series, and the presence of a basal lamina on 

 the neural. 



It is represented by a portion of the vertebral column three inches in length. 

 In this space may be counted twenty-four vertebrae Such of the latter whose 

 outlines are visible display centra, characteristic of the genus; their terminal 

 concavities conic, with apices meeting medially; zygapophyses present; and 

 their length a little greater than their depth. 



The characteristics of the species are the remarkable length and slenderness 

 of the fan-shaped neural and haemal spines, and the absence of an acute serra- 

 tion on their margins. In this species the spines have a larainiform expansion 

 at the base in their planes. In the other species here described these spines 

 are not only relatively broader and more fan-shaped, but they are acutely ser- 

 rate on the margin and constricted at the base. 



In S. r e m ex the dilated neural spines are a little more than three times as 

 long as they are distally wide, while the h;emal spines are a little narrower. 

 The neural spines stand about the middle of the centrum. The basal half ia 

 furnished with an anterior ala, which leaves the anterior margin rather ab- 

 ruptly and extends to the next spine in advance. It returns gradually to the 

 centrum and is separated from the articular face of the latter by a notch. A 



1868.] 15 



