1B 
On the Fossil Cephalopoda from Somaliland collected by 
Dr Donaldson Sminh. By G. €, Erick, Gas: 
THE fossil Cephalopoda brought by Dr. Donaldson Smith are so 
fragmentary and so very much worn that their exact determination 
is scarcely possible. They are all Ammonites belonging to the 
division Perisphinctes, a rather large section, many of whose mem- 
bers are very difficult to determine even when well preserved. 
Most of the examples are merely portions of whorls; in only one 
instance is the whorl nearly complete. Still several species can be 
distinguished. The fossils are preserved in a_brownish-yellow 
matrix, and are all labelled’ oVerta:: 
1. Perisphinctes cf. Adelus, GEMMELLARO.! 
This species is represented by at least two examples, the better 
of the two being the best specimen in Dr. Donaldson Smith’s col- 
lection. It consists of nearly an entire whorl, is very much worn, 
and has the following dimensions: Diameter, 131 mm.; height 
of outer whorl, 39 mm.; ditto above preceding whorl, about 29 mm. ; 
thickness, 38 mm.; width of umbilicus, 62 mm. The last half 
whorl has nineteen or twenty principal ribs; these on leaving the 
umbilicus are directed slightly backwards, they are a little curved, 
and each divides at about the outer third of the lateral area of the 
whorl usually into two but sometimes into three ribs, which pass 
straight over the periphery without interruption. The suture-line 
cannot be made out. It is probable that the body-chamber 
occupied at least two-thirds of the portion of the whorl that is 
preserved. 
The other example of this species consists of about half of a 
whorl with a diameter of 107 mm., and exhibits no septa. 
The species represented by these examples seems to come 
nearest Perisphinctes Adelus, Gemm., from the zone of Asprdoceras 
1 Giorn. Sci. Nat. ed Econ. Palermo, vol. viii., Pt. i., 1872, p.158, Pl. III., 
