49 
shown the existence of an eye (op. cit. p. 314, Taf. X, fig. 21 and 23, oe), which in the illu- 
stration is drawn as situated on the ventral side of the forehead »in Form yon zweien am 
oberen Theile etwas verdickten sichelf6rmigen Pigmentflecken, welche in der Mitte sich 
beriihren und eine x-formige Figur darstellen«. As a matter of course, the eye must be 
found on the dorsal surface, but I have been unable to find it on my larve, probably 
because the spirit had dissolved the pigment. 
The Antennule are always rather short; they consist typically of three joints, the 
second of which is usually short and not unfrequently coalescent with the first, in which 
case we only perceive two joints. The first, and particularly the third joint, are provided 
with pretty long sete; the terminal seta of the third joint is very long, and from the lower 
side of this joint proceeds always a single, particularly long olfactory seta (pl. I, fig. 11, b), 
which is at least double, usually several times, the length of the whole antennula; sometimes 
this seta is exceedingly long, as e.g. in Spher. dispar (pl. [X, fig. 3k) and in Spher. insignis 
(pl. X, fig. le), where it reaches further than the middle of the abdomen, nay in the last- 
mentioned species the olfactory seta in itself is longer than the whole cephalothorax. The 
antennulz are always attached pretty far from each other at the edge of the cephalothorax, 
the area between them forming what I call the front. Close to the inner margin of the 
base of the antennula we often see an oblique list; moreover, in nearly all species of 
Spheronella which are parasitic on Cumacea, the front is decorated with one or several 
rows of delicate and peculiar processes, which decoration reaches its highest development in 
Spher. decorata (pl. VILI, fig. 3i and fig. 31). In Spher. modesta these processes are replaced 
by transverse lists (pl. [X, fig. 21). 
The Antenne proceed behind, and usually at the same time somewhat obliquely 
inside the antennule, but never from the base of the rostrum. Sometimes they are conside- 
rably shorter. than the antennule, sometimes about the same length, and in the genus 
Homoeoscelis (pl. 11, fig. 11 and pl. XIII, fig. 1h) more than double the length. In Spher. 
marginata (pl. XIII, fig. 6g) only two joints are found, in all other species they consist of 
three or four joints, three of which are always distinct, but it is often difficult to make out 
for certain, whether the eminence from which the supposed second joint proceeds, is a real 
joint, or in other words, if the apparent basal joint consists of two joints; as, however, 
Spher. antillensis has four very distinct joints (pl. IL, fig.2e), this is probably the typical 
number. The terminal joint is nearly always short and usually ends in a long, thick seta, 
beside which we frequently find a shorter one. The next joint is now rather short, now 
long, or very long, and where the antenna is long, it is on account of the length of this 
joint, as the basal joint, or where there are four joints, the two first of these are never 
elongate, but sometimes (pl. IX, fig. 2i and fig. 3k) comparatively broad. In Mysidion 
(pl. XII, fig. 2h) the antenne are very small, and in Spher. microcephala (pl. VIII, fig. 21) 
almost rudimentary, in both cases 3-jointed, with an exceedingly short terminal seta. 
The Rostrum seems to correspond only with the more distal part of this organ in 
7 
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