1863. ] On Dr. Gerard’s collection of Spiti fossils. 133 
cies. Moreover, from such fragments of shell as remain on one of 
our specimens, it appears that this was smooth in A. Gerardi as in 
the Triassic forms, whereas that of A. sternalis is ornamented ex- 
ternally with fine ribs. 
The ventral lobe of the septa of A. Gerardi is extremely short, 
barely half as long as the superior lateral lobe, and is divided almost 
its entire length. The lateral lobes are nearly equal and fan-shaped 
at the extremity, and the saddles simple and compressed in form. 
Four specimens are in the Gerard collection; one of the smaller, a 
distorted specimen, was figured in the Asiatic Researches; another 
is here represented. These are both young and do not shew the 
radiate undulations which characterize the adult shell.* 
15. CrratiresP Himatayanos, n. s. Plate II. figs. 7, 7a. 
C. testa discoidea, compressa, carinata, tuberculato-costata. An- 
fractibus amplexantibus, complanatis. ‘Tuberculis internis apud 4 
anfractuum 10: externis apud peripheriam 20. Costis haud promi- 
nentibus, incequalibus, plerumque bi vel tri-furcatis. Ventre anguste 
earinato, haud suleato. Umbilico parvo; marginibus rotundatis, 
Apertura angulateé ovata, anticé complanata. 
Diameter of shell, Jinch 6 lines. 
4 of outer whorl 9 
Thickness, Ces 
Width of outer whorl = ,°° of the diameter of the shell. 
100 
9? 
The specimen of this shell in the Spiti collection, although in a 
very fair state of preservation, does not present so clean a surface on 
that part on which alone the sutures are visible, as could be desired 
for the satisfactory determination of the genus. There is, however, 
no trace of any foliation on the saddles, so far as they can be seen, 
while the lobes of one part are distinctly dentated like those of the 
typical Ceratites. It is clearly distinct from C. Jaquemonti, Von 
Buch, the only known Himalayan species of the genus, which accord- 
ing to its discoverer, whose name it bears, was found associated with 
Ammonites biplex, and a number of other Oolitic forms of Ammonites. 
In form and ornamentation, C. Himalayanus, is closely allied to C. 
Wodosus, the type of the genus, but differs in its narrower ventral 
region and keeled periphery. 
* The largest specimens were only discovered after the plates had been finished. 
s 2 
