ialontolngia ndita,

220
REVISION OF THE JURASSIC CEPHALOPOD
Only the following three species are here described :­
GeRm Erymnoceras Hyatt.
E dorothere, sp. nov.
Genus Pachyceras :Bayle.
P. indicum, sp. nov.
P. distinctum, sp. nov .
. Ge:flUS : EYMNOCERA.S Hyatt.
ERYMNOCERAS DOROTHElE, sp. nov.
(PI. VIII, figs. 4a, b).
1914. Holcostephau,us 1 sp. Smith (b), p. 813' . .
The unique specimen on which this species is based, was recognised by
Mr. Smith as entirely new to the Kachlt fauna and promptly recorded. He
compared it to Spiticeras · spitiense (Uhlig) but directed attention to various
points of distinction, such as the vertical umbilical wall, croWn.ed by about
eleven sharp tubercles that· are elongated spirally not radially.
The mu.surements
are :-65- ·40-- 43 1- ;34. The thickness, oWing to the end of the
contracting body-chamber being worn, was probably &lightly under-estimated
by Mr. Smith.
The septate depressed inner whorls are oorroded and the sutureline
is unknown
The form is intermediate between such Erymnoceras as E. renardi Nikitin
sp. (1'881, p. 120, pl. IV, figs. 24a, b) with open umbilicus, and the involute
Pachyceras jarryi (Deslongchamps ' MS) and P. crassum (R. Douvme, 1912, pp. 37
and 4!, pl. VII) which have lost the coronate umbilical edge, at least on the
outer whorls. One of the ·evolute varieties of E. coronatum (Bruguiere) in
the wider sense, figured by R. · Douville ·(1913, p. 31, text-fig. 23a only) shows
great resemblance to the present species but has more distant ribs and less
cadicone inner whorls.
This was identified with E. ajax d'Orbigny sp., which
is probably not identical with the Rasenia-like Amm. ajax Schloenbach (1865,
p. 187, pl. XXXI, figs. la-c), and was erroneously identified by Loczy (1915
p. 347) with the cadicone E. coronoides (Quenstedt). The lectotype of E. ajax,
figured in the Annales de Paleontologie (1913, pl. IX, figs. 12-13) is not closely
comparable to the present species and Petitclerc's coarsely ribbed form (1915,.
p. 106, pl. XI, :fig. 4) is again quite different.
It is interesting to compare the side-view of the present transitional species
with the forms figured by R . . Douville in 1912 (b, p. 245, text-fig . . 6) to show
the passage from the Callovian Erym'aoceras to the Divesian Pachyceras.
Horizon.-Divesian ( ' athlet& beds '). In England, large examples of E.
reyinaldi (Morris), bearing impressions of finely-ribbed Kosmoceras occur in
fraasi zone, together with gigantic Proplanulites.
Locality.-Fakirwadi Ridge.
·
the