49 wi 
1878. } SYA [Cope. 
former at anangle. The inferior face is convex transversely, and slightly 
concave antero-posteriorly. The tubercular rib facets are oval, and are 
narrowed downwards and forwards. The side of the neurapophysis de- 
scribes a curve which rises a little to the superior part of the extremity of 
the diapophysis. The zygapophysial surfaces are as wide as long, and a 
little oblique. The neural spine is not very elevated, and is very robust ; 
its section is a longitudinal oval. Its summit is truncated and thickened 
laterally. 
Measurements. M. 
{PANS ViETSC renters mel sre rererclesiaicion SUD 
Diameter of intercentrum + : 
antero-posterior............ .023 
Expanse or dia popnySesi sm... 11 =) <= Sra acaavahe Sepaaveva whe 
Length of tubercular surface of do. ci). .s050...¢04 <5 O22 
Elevation of neural arch.............. Bias esa Aooonte, Olli! 
= SOEPESMING se fel stochus ceric ise ee et ene OA) 
Antero-posterior diameter of summit of do............. .044 
PISCEs. 
CTENODUS PERIPRION. Sp. nov. 
This large species is indicated by a fine palatal tooth of the left side. Its 
outline approaches that of a right-angled triangle, but the hypothenuse is 
deeply incised by the interradial notches. The plate is rather thin, and 
is moderately concave on the inferior face. The ridges number seven, all 
of which are directed outwards and forwards. They are separated by 
strong grooves, and have a perfectly smooth and uniform crest, and be- 
come more elevated at the distal extremities. The latter are steeply de- 
curved and serrate, both faces being invested with a polished enamel-like 
layer. This substance is only visible in an edge view, and covers one-half 
the depth of the margin, being excavated by the extremities of the radia- 
ting grooves. The superior face is flat. 
The absence of serration from the radiating ridges of this species is a 
striking feature, allying it to the genus Ptyonodus,* where the teeth are 
wanting. 
Measurements. M. 
Length of dental plate......... Males ckereterete tallest feteteser stele 5 aE 
Width ‘ ag Meneteiecia) stars ialete ote (era stats Sesto eaiereicre .018 
Thickness at inner border.......... Bere orerarey Tce cra ververete 005 
a ** external border of penultimate crest....... 007 
From the same locality as the species above described. 
CTENODUS PORRECTUS. Sp. nov. 
Two teeth of the left palate indicate this species. The tooth is char- 
acterized by the smail number of its crests (six), of which only one, 
the very small first, is directed backwards, and the last four are di- 
rected forwards. The crests are separated by deep grooves, which ter- 
minate in deep emarginations. The anterior crest is produced much 
beyond the extremity of the penultimate, and the latter as much be- 
*Proceed. Amer. Philos. Soc., 1877, p. 192. 
