41 
we see instead of a single line a wider or narrower band of hair going from the posterior 
extremity of the lateral margin up across the back, and behind this line or band is a larger 
or smaller transverse naked area, whereas the other parts of the trunk: the back, the sides, 
the posterior extremity and the ventral surface, are closely covered with shorter or longer 
hairs, with the exception of a transverse band in front between the first pair of legs — and 
frequently their surroundings — which is naked. These hairs are usually simple; in Spher. 
frontalis (pl. VII, fig. 6a, fig. 6b and fig. 6h) and in Mysidion commune (pl. XI, fig. 3 @ and 
fig. 3h) the trunk is closely covered all over with transverse minute knots, each of which 
bears several (in S. frontalis at least many of them ten) fine hairs. In Spher. Giardii the 
trunk is covered with 2- or 3-branched hairs similar to those mentioned above in the 
female of S. Calliopu and in S. irregularis. In the male of S. Calliopii (pl. III, fig. 3h 
and fig. 3i) the hairs of the boundary line between the head and the trunk are particularly 
long, whereas the dorsal surface and the posterior extremity are covered with fine. dots 
resembling the roots of hairs, though I have been unable to find any hairs, and across the 
back to the exterior angles of the first pair of legs we find a narrow, naked band; the 
ventral surface behind the caudal stylets is provided with ordinary hairs. In Spher. microce- 
phala (pl. VIII, fig. 2¢ and fig. 2h) the hair-covering is less developed than in any of the 
other species, as only the hindmost part of the lateral borders of the head and the ventral 
surface of the trunk are covered with hairs, the other parts of the body being naked. Ina 
few species we find hairs in front of the base of the maxillipeds, and in Spher. chinensis 
(pl. ILL., fig. 1a) and kindred species there is a bunch or a short band of hairs outside the 
base of the maxillule., 
As to the internal structure of the male I confine myself to the following observa- 
tions. In a well-preserved specimen we usually perceive through the transparent skin two 
larger or sinaller globular bodies in the middle of the trunk or somewhat more to the front; 
in Stenothocheres they are situated close to the front of the abdomen behind the base of the 
second pair of legs. I will call these bodies spermatothece, though I cannot make out 
whether they have really the function of such organs, or whether they are the testicles them- 
selves. I have illustrated them in several forms, as Spher. paradoxa (pl. II, fig. 4 h, q), 
S. capensis (pl. VI, fig. 1 ¢), S. Bonnieri (pl. VI, fig. 1a, q), S. frontalis (pl. VII, fig. 6 a, q) 
and Mysidion commune (pl. XI, fig. 3g, q); in this last species the spermatothece are 
particularly large and obliquely situated (probably a case of anomaly or of accidental pressure 
in the figured specimen, for in the next species: Mysidion abyssorum (pl. XII, fig. 2 ¢, q) 
they are normal). In Aspidoecia Normani the specimen illustrated (pl. XII, fig. 3k) showed 
a single, but very large spermatotheca (q), but in a couple of other specimens I saw two 
considerably smaller and normally situated spermatothece. In Spher. paradoxa I succeeded in 
finding the genital apertures very close to each other on the posterior wall of the depression 
which runs across the front part of the trunk on its ventral surface. From each spermato- 
theca a rather short duct goes forward and obliquely towards the median line to its aperture. 
6 
