184 PSEUDOCERATITES OF THE CRETACEOUS. 
This cast was considerably worn. The right side was free of encrusting 
ostreans; on the opposite (left) side there were a few, some of which were 
removed. No shell was found between these and the cast. They had 
evidently grown upon this cast and not upon a living or dead shell. This 
can also be seen by studying the remaining shells, one complete lower valve 
and part of another. 
Locality: Nine miles from Austin, Tex., on the Beecaves road. 
Age: Comanche Peak limestone, Fredericksburg group of Comanche 
series, Lower Cretaceous. 
METENGONOCERAS ACUTUM n. sp. Hyatt. 
Pl. X XVI, fig. 8; Pl. XX VII, figs. 1,-2. 
The type specimen of this species in Boll collection in the Museum 
of Comparative Zoology is a fragment, but this shows the whole diameter 
to have been approximately 100 mm. ‘The outer volution from line of 
involution to venter is 54 mm, the umbilicus 5 mm., and the same volution 
opposite must have been about 40 to 41 mm. 
The form is much compressed and involute, with more acute venter 
than in M. inscrivtum. The umbilical shoulders also in this species are 
more prominent and entire, and short but distinct, broad, fold-like costze 
are present near the umbilical shoulders, but do not cross them. There 
are no tubercles on the fragments observed. 
The marginal lobes of the first lateral saddles on both sides are narrow 
and divided by a minute marginal saddle or bifid. he first laterals are 
unsymmetrically trifid, the second to the fourth are symmetrical and quad- 
rifid, the fifth is of the same type but not regularly divided. All of these 
are very narrow at the bases between the expanded bases of the saddles and 
spread out apicad into the marginal divisions. The sixth lobe is narrow 
and bifid, with a small marginal saddle, and the seventh similar, but with a 
larger tongue-like marginal saddle, and the minor lobes on either side of 
this are also subdivided or bifid. The eighth and ninth are distinctly but 
very faintly trifid, and much longer than the narrow marginal lobes — 
described above as dividing the broad saddles of this part, which are faintly 
bifid. The tenth lobe was visible but not distinct enough for description. 
Both specimens were too much crushed in the central parts to give 
any accurate data for the description of the younger stages. Nevertheless 
