[Xs 
Cope. | 528 [April 5, 
yond the fourth. The extremities of the crests extend obliquely to their 
bases, and support four or five dentiform processes. The dense shining layer 
extends inwards as far as the bases of the serrate portions. The inner 
face of the anterior crest is oblique, and the posterior inner border curves 
outwards to behind the first crest, leaving a shelf-like continuation of the 
palatal surface of the tooth. 
Measurements. M. 
Wene thon tooul ieee rer SOURED GO seEboooABodae alle 
Width at third crest ..-..... Nota Jaan steteeratsteiete age Sore O15 
Depth oppositerthirdsereste ce cis) sroheeetncreh ts sensors . .004 
This species must be compared with C. fossatus Cope, and C. serratus 
Newb. The latter is a wide tooth with less oblique, and fully serrate 
crests. The former is a narrow species, but the anterior crests are not 
nearly so extended ; it is deeper, and the inner side is vertical, and with- 
out the posterior palatal lamina seen in the two species named. 
CTENODUS DIALOPHUS. Sp. nov. 
Represented by a single left tooth in excellent preservation. Its charac- 
ters are very marked. It is of narrow form, and has more numerous crests 
than any other known American species. They number ten, and there are 
two or three other rudimental ones at the posterior extremity. They are all 
more transverse than usual, five being directed forwards, and five slightly 
backwards. The crests are acute, but the grooves and emarginations are 
not very deep. The crests are entire, except at the obliquely truncate dis- 
tal extremities, where there are from two to four dentations. The shining 
layer does not extend within these. The inner border of the tooth is ver- 
tical, excepting posteriorly, where the inner border of the crest-bearing 
portion turns outwards, leaving a narrow ledge of the palatal face. The 
latter is concave in cross section. 
Measurements. M. 
Length (.004 at one end inferential)....... SdcnShadaOSe 033 
ANAC Hoy NPAT EN OHESocogeceboaodous Miatesrsi shores (a/cke cio eieveere -O10 
Depth opposite tith Crest. rye ite els apa foteiavsko etek 004 
It is not necessary to compare this species with any other. 
OBSERVATIONS ON THE PELYCOSAURIA. 
In addition to the type of humerus described under the head of the genus 
Clepsydrops, several other remarkable forms occur in the collection, which 
are probably referrable to the various genera of Pelycosauria. I give 
the following tabular analysis of them : 
A, No condyle ; a supracondylar foramen. No special proximal articu- 
lar surfaces. 
INOs lenCClepsy/ Gros) Gee. c.s sess. erie Sogiews saves ne siete SPECIMEN GaGa: 
AA, Condyles and supracondylar foramen. 
a, The shaft uninterrupted. 
No. 2. Condyles longer; smaller....... NO Aaa nates dhajeie essisis\yeiets Dol OF 
Nows) (Condylesswider=slarcere. ..ie cece aie leveieeiee Seas 6 Sp. 4. 
