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 Maaxille ave 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 Spheronella insignis, pl. LX, fig. 4c). 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 Spher. 
Munnopsidis, with some peculiar cylindrical bristles or fine processes (pl. X, fig. 4b); in 
Spher. decorata (pl. VIII, fig. 3e) and in S. modesta (pl. LX, 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 Spher. dispar (pl. LX, fig. 3f) 
the apex is blunt, but has several fine, setiform points. In Spher. marginata (pl. XIU, 
fig. 6d) the maxille are quite rudimentary. 
The Maxillipeds are well developed in Spheronella and in Homocoscelis. They are 
articulated on the posterior part of the sub-median skeleton and are usually somewhat 
closer to each other than the two maxilla. 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 Spheronella which live on Cumacea, 
is provided with fine points, besides being sometimes broad and flat (pl. XIII, fig. 6d). The 
iast 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 Spheronelle 
living on Cumacea the joint expands a little towards its somewhat flattened and rounded 
extremity, along the margin of which we see numerous fine and short, setiform processes. 
A somewhat similar structure is noticed in Spheronella Munnopsidis (pl. X, fig. 4b). In 
Spher. microcephala (pl. VIL, 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 (pl. XI, fig. 1a, ¢ 
and fig. 2d), and reduced to two very small or quite diminutive joints. 
