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 Sphcer. 

 frontalis (pi. VII, fig. 6 a, fig. 6 b and fig. 6 h) and in Mysidion commune (pi. XI, fig. 3 g and 

 fig. 3 h) 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 Sphcer. Giardii the 

 trunk is covered with 2- or 3-branched hairs similar to those mentioned above in the 

 female of S. Calliopii and in S. irregularis. In the male of S. Calliopii (pi. Ill, fig. 3 h 

 and fig. 3 i) 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 Sphcer. microce- 

 phala (pi. VIII, fig. 2 g and fig. 2 h) 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. In a 

 few species we find hairs in front of the base of the maxillipeds, and in Sphcer. chinensis 

 (pi. III., fig. 1 a) and kindred species there is a bunch or a short band of hairs outside the 

 base of the maxillulse. 



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 smaller 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 spermatothecce, 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 Sphcer. paradoxa (pi. Ill, fig. 4 h, q), 

 S. capensis (pi. VI, fig. 1 c), S. Bonnieri (pi. VII, fig. 1 a, q), S. frontalis (pi. VII, fig. 6 a, q) 

 and Mysidion commune (pi. XI, fig. 3 g, q); in this last species the spermatothecse 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 (pi. XII, fig. 2 c, q) 

 they are normal). In Aspidoecia Normani the specimen illustrated (pi. XII, fig. 3 k) showed 

 a single, but very large spermatotheca (q), but in a couple of other specimens I saw two 

 considerably smaller and normally situated spermatothecse. In Sphcer . paradoxal 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 



