1884.] 35 LCope. 



The typical specimen of this species was found by Mr. W. F. Cummins 

 in the Permian beds of Northern Texas. 



Clepsydrops macrospondylus, sp. nov. 



This species, like the last, much exceeds the C. natalis in dimensions. 

 The bases of the neural spines are enlarged, so that it is probable that the 

 spines were not elongate as in the species of Dimetrodon. Intercentra are 

 present throughout the dorsal and caudal series of vertebrae. The den- 

 tary bone supports one or two large teeth near the extremity. These 

 characters furnish the reasons for referring the species to the genus 

 Clepsydrops. 



The individual by which the species is known, is represented by an axis 

 vertebra, twelve continuous dorsal vertebras ; nine other continuous verte- 

 brae, of which three are lumbar, two sacral, and four caudal. Also by a^part 

 of the ilium, and by the greater part of a dentary bone. All of these speci- 

 mens were found together, and possess an identical mineral appearance. 



That this reptile belongs to a distinct species from the G. leptocephalus 

 is readily determined by the form of the dorsal vertebrae. The centra are 

 a little longer than those of that species, but have a smaller vertical diam- 

 eter. The latter is three-fifths of the former, while in the G. leptocepha- 

 lus the two dimensions are reversed, the depth being a little in excess in 

 corresponding parts of the column. The dentary bone, on the contrary, 

 is more robust than that of the G. leptocephalus, and supports, probably, 

 a small number of teeth. 



The edges of the centra are not undulate or laterally flared. The cen- 

 tra are strongly compressed, and in the anterior part of the column have 

 an obtuse hypopophysial keel. The intercentra display equal width of the 

 inferior surface; and are abruptly rounded at the extremities. The last 

 one preserved is between the second and third caudal centra. It is shorter 

 and "w ider than the others, and does not display any trace of a chevron 

 bone. The diapophyses are opposite the neural canal on the thirteen an- 

 terior vertebrae preserved. Each one sends a horizontal rib forwards to 

 the prezygapophysis, and another obliquely forwards and downwards 

 which stops short of the edge of the centrum. These ribs enclose a fossa 

 in front of the diapophysis. Posteriorly the anteroinferior rib grows more 

 robust, and evidently supports part of the tuberculum of the rib. There 

 is no facet for the capitulum until the antepenultimate vertebra of the 

 anterior series is reached. Here and on the penultimate the anterior 

 border is flattened into a facet, and on the last of the series, the facet 

 marks the summit of a distinct tuberosity, which is produced by the cut- 

 ting away of the border below it, to accommodate the intercentrum. 



The three lumbar vertebrae preserved are different from the dorsals in 

 their greater abbreviation. This character is not unknown in other species 

 of Pelycosauria. The centrum is contracted, but not compressed, at the 

 middle. The diapophysis is altogether on the centrum, and supports no 

 rib-facet. Its anteroinferior buttress is well developed, extending to the 



