Ser. XV. HIMALAYAN FOSSILS, Vol. IV. THE FAUNA OF THE SPITI ...

HIMALAYITES. 137
particularly copiously ramified. The second lateral lobe is placed somewhat
obliquely. The sub-symmetrically branched slender dorsal lobe is as long aa
the first lateral lobe.
Himalayites depressus is distinguished from H. Seideli by its much more
depressed volutions, its less numerous intercalary ribs and the structure of its
suture-line ; from H. kutianus by its much greater thickness, the structure of
its suture-line, the more radially disposed ribs and the less numerous intercalary
ribs. The characters which distinguish it from H. Hollandi are stated under
the latter species.
Himalayites depressus occurs in Spiti.
HIMALAYITES HYPHASIS, Blanford sp.
(Plate XXXVIII, figs. 2 a, 6, 3 a—d.)
18C3. Ammonites hyphasis Blanford, Journ. Asiatic Society of Bengal, Caloutta, XXXII, plate IV,
Dimensions :—
ligf. 2, 2a, 2b, p. 132 (non Ammonites hyphasis Stoliczka).
of fig. 3. of fig. 2.
Diameter 49 mm. 45-0 mm.
Width of umbilicus . . . . . . . 21 „ 20 „
Height of lust volution measured above umbilical
suture IT . 14-8 „ 15
Thickness of last volution measured over the ribs . 17-5 „ 18 „
The shell of this small species consists of roundish volutions which overlap
one another only slightly, are gently arched at the flanks, somewhat depressed
on the ventral face and descend by the rounded umbilical wall to the wide
umbilicus. The breadth of volution on the anterior part of the shell is only
slightly greater than the height. Straight, sharp and high ribs traverse the
flanks in a radial direction and pass right across the external margin. Some
of the ribs split up into two secondary ribs at about the middle of the flanks,
whilst others remain undivided. In Blanford's type specimen (fig. 3) simple
and branched ribs alternate fairly regularly. Only at three places two bifid
ribs follow each other directly, whilst near the front end of the shell on a part
of the latter belonging to the body-chamber four simple ribs are developed one
after the other. The point of bifurcation may be shghtly thickened, this swell-
ing even having developed into a spine-like protuberance near the anterior edge
of the specimen depicted in fig. 2. Along the median line of the external mar-
gin, the ribs are not completely interrupted but only shghtly weakened or fur-
rowed. On either side of the median line, a feeble, just noticeable swelling
affects the ridge-like ribs. On the last whorl occur 28 to 30 main-ribs.
The suture-line corresponds in its main outline to the generic type, but is
only scantily ramified. The saddle-bodies are very broad and cut into by short
secondary lobes. On the external saddle, two secondary lobes are especially
prominent, as is also one secondary lobe on the [ lateral saddle. The first lateraL