Cope. | ; 514. {April 5, 
ischia in Clepsydrops natalis, are of a size appropriate to the present spe 
cies. They include both the ilia, ischia and pubes in one mass, forming a 
compressed boat-shaped body with a prominent inferior keel. 
The prominent character which distinguishes this species is the shortness 
of the ischiatic symphysis. Its extent anterior to the acetabulum is only 
one-half the diameter of the latter, while it equals that diameter in the 
C. gigas. It follows from this, that the crest arising from the anterior 
border of the acetabulum is abruptly decurved a little anterior to the latter, 
and descends to the inferior keel at a very steep angle. At its point of de- 
curvature is a prominent tuberosity. The front of the symphysis pubis 
presents an obtuse keel, which terminates short of the apex. The inferior 
border of the acetabulum is not sharply defined, except at its posterior 
portion. 
Measurements. M. 
Motall lenieth: tt ARE Sek Se a ae ptt eden, ots eae oe 260 
Length from posterior border of acetabulum forwards.. .148 
Wongrdiametenoteaceta ulimit sas seit cis ttreereret cise .095 
Total vertical diameter to superior border of acetabulum .135 
Wength of anterior sy miphysisine cisc.Ae se <r baw c mies 085 
From the same locality as the last species. 
DIMETRODON RECTIFORMIS Sp nov. 
This species is represented by portions of the vertebral columns of three 
individuals at least. Its size exceeds considerably that of the Clepsydrops 
natalis, equaling that of the C. (? Embolophorus) limbatus Cope. Of the 
latter species I possess numerous vertebree, and they all differ in a marked 
manner from the present species. 
In Dimetrodon rectiformis, the depth of the centra does not exceed the 
length. The margins of the articular faces are not twisted, and the articu- 
lar faces of the zygapophyses are horizontal. The opposite is the case in 
the C. limbatus. The spaces for the intercentra are smail; they are large 
in (@. limbatus. The vertebra described as typical is a posterior dorsal. 
Here the diapophyses is nearly sessile, and beiow the line connecting the 
zygapophyses. Its costal articular surface is narrowed downwards and 
forwards, almost reaching the recurved border of the anterior face. The 
neural spine is much elevated, and the sides of the centrum are concave. 
The inferior articular borders are connected by an acute nearly horizontal 
edged keel. 
Measurements. M. 
antero-posterior....... SedeOdonn2 000 .081 
Drameteronrcenthum! transversely. cli ci cel-teleleieielereloieteioerel= .0384 
( VELtICAle ei. teltencele dha SteTe ees cSt 026 
Expanse of posterior zygapophyses.......-......25--- .030 
henothiotbase oi meural Spins se. ocictele eaiatelereerrste me 0go 
From the same region as the other species here described. 
