136 PSEUDOCERATITES OF THE CRETACEOUS. 
Besides the type mentioned above, this group contains Ger. galeatus 
(Karsten) (von Buch’s figure of this species is too poor for comparison), and 
Ger. veleziensis n. sp. Hyatt (Pul. didayi Gerh., op. cit., pl. 3, fig. 4). Amm. 
didayanus VOrb. belongs to genus Nicklesia. Amm. didayanus Karsten is 
probably a younger stage of the species figured by Gerhardt, and it came 
from the same locality, Velez. 
Similar species have been cited from other countries by Gerhardt, but 
these are unknown to me. 
All species are of Barremian age and found in Colombia or Chile. 
The sutures have been well figured by Gerhardt and are quite different 
from those of C. tuberculata and H. provincialis. 
PULCHELLIID-A. 
This family has highly involute compressed shells. The costee, when 
these are present, are acquired at a comparatively late age, and the tuber- 
cles, when present, are single elongated crests on the ventro-lateral angles 
of the coste. The coste usually cross the venter even when there is a 
channel on their outer surfaces. The sunken intercostal furrows that cross 
the venter also are not as a rule affected by the channeling of the coste. 
The sutures are of the same type as in Heinzia, but with somewhat 
more complex outlines. I have had no opportunity to examine the dorsal 
sutures. 
The primitive form is Psilopulchellia,* which retains the smooth keelless 
condition of its own young throughout life. This stage is transient in the 
development of other genera. In Nicklesia it is followed by a stage with a 
flat venter, and this is then followed by the development of lateral coste 
that cross the venter without tubercles or channels, or the latter may be 
developed directly from the previous stage. 
Subpulchellia has similar stages followed by a channeled venter due to 
the development of two slight ridges. 
Pulchellia develops lateral costee that cross the venter, but these are 
concave on the venter and have lateral tubercular crests in place of the 
ridges of Subpulchellia. The intercostal furrows also cross the venter, but 
are usually convex on the venter between the coste. The tubercles have 
been universally ont erroneously spoken of as keels. They are really not 
«The author filed to seagate or cite any species belonging to Palenuienenin —T. W.S 
