29 



position of the rostrum with the lateral margins of the head (comp. the rostrum in the 

 numerous figures of males seen from left side). 



The Maxillce are always (except in one single species mentioned below) well deve- 

 loped, often very powerful. They are situated far from each other, somewhat behind the 

 base of the rostrum, on the outer margin of the sub-median skeleton, the expansion of 

 which reaches their inner margin and frequently extends behind their posterior margin. 

 Typically they have three joints, of which the first one is very thick, often not much longer 

 than broad; the second and third joints together are usually shaped like a slender, distally 

 somewhat curved cone, which can be folded up like a claw against the oblique terminal 

 margin of the basal joint, and as a rule these two joints are coalescent, though sometimes 

 we find them very distinctly separated (e. g. in Sphceronella insignis, pi. IX, fig. 4 c). The 

 basal joint is often provided with one or two protruding knots or taps, and its terminal 

 margin at the articular membrane is frequently furnished with hairs, or, as in Sphcer. 

 Mimnopsidis , with some peculiar cylindrical bristles or fine processes (pi. X, fig. 4 b); in 

 Splicer, decorata (pi. VIII, fig. 3e) and in S. modesta (pi. IX, fig. 2d) a part of the articular 

 membrane between the first and the second joint is decorated with rather numerous small 

 chitinous taps. The terminal joint usually ends in a point; in Sphcer. dispar (pi. IX, fig. 3f) 

 the apex is blunt, but has several fine, setiform points. In Sphcer. marginata (pi. XIII, 

 fig. 6 d) the maxillae are quite rudimentary. 



The Maxillipeds are well developed in Sphceronella and in Homoeoscelis. They are 

 articulated on the posterior part of the sub-median skeleton and are usually somewhat 

 closer to each other than the two maxillae. They consist typically of four joints, of which 

 the basal one is thick, very long and always distinctly longer, often much so, than the 

 others together; these can be folded up against it in a very acute angle. The basal joint 

 is often decorated with processes, spines, rather long hairs, shorter or very short hairs, or 

 very fine, conical taps; the hairs and taps are arranged in spots, stripes or rings. The 

 second and third joints are slender, distinctly or indistinctly articulated or quite fused 

 together without the slightest distinction. The third joint has generally on the inner side 

 of its distal end a spine, which in those species of Sphceronella which live on Cumacea, 

 is provided with fine points, besides being sometimes broad and flat (pi. XIII, fig. 6 d). The 

 last joint is more slender than the others , somewhat curved and often ending in a point 

 with one or two spines on the inner side behind the point; in most of the Sphceronellce 

 living on Cumacea the joint expands a little towards its someAvhat flattened and rounded 

 extremity, along the margin of which we see numerous fine and short, setiform processes. 

 A somewhat similar structure is noticed in Sphceronella Mimnopsidis (pi. X, fig. 4b). In 

 Sphcer. microcephalia (pi. VIII, fig. 2d) the maxillipeds are weak and comparatively rather 

 small, second and third joints coalescent and very short, the last joint very small and 

 stunted. In the genus Choniostoma the maxillipeds are quite rudimentary (pi. XI, fig. la, g 

 and fig. 2d), and reduced to two very small or quite diminutive joints. 



