334 PROCEEDINGS OF THE MALACOLOGICAL SOCIETY. 
(10mm. long by 2 mm. wide); then a thinner and more membranous 
tube (3mm. long by *5mm. broad); and then, at the entry of the 
hepatic mass, a dilatation 5 mm. long and 3 mm. broad. I could not 
see any folds or plates in any part of this apparatus, but it was not 
well preserved. The hepatic mass lies on the top of the digestive 
tract, as in the last species, and is grooved to receive it. The prostate 
is granulose and T-shaped; the verge elongate and conical ; no groove, 
though doubtless present, could be distinguished on it. The shell is 
a mere convex plate, as in Ap/ysta, and entirely membranous, without 
a trace of calcification. But the individual is small and probably 
immature, so that calcification may perhaps set in later. 
Dorrptum (?) cyanrum, Von Martens. 
I only know Von Martens’ description of this species and of 
D. nigrum as they are reproduced in Pilsbry’s ‘‘ Manual of Con- 
chology,” vol. xvi. The details given are so few that identification 
without reference to the original specimens is hardly safe, particularly 
as my specimens do not show any ‘‘numerous anastomosing net-like 
wrinkles.” On the other hand, they come from much the same 
locality, East Africa, and they exhibit the same remarkable variety of 
hue, ranging from uniform bluish black to an elaborate coloration 
analogous to that of Von Martens’ var. vittata. 
Of my specimens captured in Zanzibar (Chuaka and Jembiani), one 
was of a uniform transparent black with a beautiful purple inidescence, 
with no markings at all. In another the ground colour was the same, 
but the various lobes were edged with bright blue blotches. In two 
others, in addition to these markings two sandy crescent-like spots were 
present, one on each of the dorsal shields. Of three specimens caught 
at Jembiani, one had in addition to the vivid blue blotches two long 
broken lines of orange yellow on the head and sides, besides a few dots 
of the same colour on the back; a second had in addition numerous 
irregular greenish blotches. In a third the yellow was greyish and 
the green blotches smaller and fewer. 
In alcohol the largest specimen measures 24mm. in length and 
15mm. in breadth. The front shield is 14mm. long, the hind shield 
8mm. The margin of the front shield is fairly ample, but the hind 
shield is hardly distinguished from the surrounding area. The 
posterior processes form a disk much as in D. depictum. There are 
no distinct lamelle or other organs which can be called rhinophores. 
The gill is large and white. The seminal groove is not white as in 
many other dark species, but of the same colour as the surrounding 
parts. ‘lhe pharynx is colossal compared to the size of the animal 
(length 12, breadth 15mm.), but is not very muscular. The shell is 
of a fair size, a large membranous plate being attached to the calcified 
part, which latter is 9mm. long. There appears to be no spire. 
The prostate is double, or at least deeply bifid; the verge is long 
and grooved.' 
1 Since writing the above I have read Professor Bergh’s description of the species 
(Semper’s Reisen, rv, iii, 2, pp. 303-5), which in essential points agrees with mine. 
