105 
PART 2.] Griesbacit: Palaonlolorjical notes, Lower Trias, IVmalayas. 
chamber amounts to exactly one-half of the entire eyolution. Siphon situated at 
about f of the height (fig. 3). The septa show nearly the same lines as Nautilus 
sM?)arai«s, Keys.the pointed antisiphonal lobe marks this species at once as 
belonging to the forms of which N. aratus, Schl., is the type. The number of 
septa are about thirty in a whorl. 
The only character which distinguishes this species from Beyrich’s species 
N. quadrangulus^ is the fact, that the German Muschelkalk form seems more 
compressed than our species, so far as I can judge from the figure given. But 
there can be no doubt that the German Muschelkalk species is a descendant 
of this lowest Trias form. 
Likewise Nautilus sf itiensis, Stol., is probably also only a later stage of 
development of this species, which is common in the Werfen horizon of the 
Tibetan Himalayas. 
With the exception of the angular shape of the section of the whorls which 
is so marked in the Indian species, it agrees very nearly with Nautilus subarat us, 
Keys., both in general shape and course of the lobe line. In fig. 2 I have 
shown another specimen, which I cannot separate at present from the larger 
form in spite of the indication of a hexagonal outline of the section of the 
mouth as shown in the figure. It is probably only a younger individual of the 
same species. 
It is very numerous in Bed 2 (horizon of Posidononiya awjusta, Hau.) of 
the lowest Trias. 
Class; CEPHALOPODA. 
Order; ? 
Family ; AMMONITIDJE. 
Tribe: PIKACOCERATION. 
Genus ; OTOCERAS, n. g.= 
Amongst the numerous forms found in Bed 2 (horizon of Posiclonomya 
angusta, Hau.), one of the most remarkable groups is that for which I propose 
the above name. Occurring, as they do, in a bed belonging to the lowest Trias, 
they form the connecting link of a group of forms, the first of which appear in 
the paleozoic epoch. 
The earliest species belonging to the ti’ibe of Pinacoceratidce appear in the 
Devonian, whore we find the Sageoeras Sagittarius, Sandb. 
In the Permian of Armenia we find again several species, and representa¬ 
tives of it are found in India (Salt-range) and pass on into Upper Trias, where 
many species belong to that genus. 
The species described under the above generic name appear in the lowest 
Trias as companions of a number of early Triassic types, in the same bed with 
' Middendorf’s Iteise iu Sibirien, PI. IV, fig. 3. 
2 Abb. Akiidemie, Berlin, PI. Ill, fig. 5. 
^ OSs, diTos — ear. 
