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 von zweien am 

 oberen Theile etwas verdickten sichelformigen 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 larvae, probably 

 because the spirit had dissolved the pigment. 



The Antennulae 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 setae; 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 (pi. I, fig. 1 1, b), 

 which is at least double, usually several times, the length of the whole antennula; sometimes 

 tliis seta is exceedingly long, as e. g. in Splicer, dispar (pi. IX, fig. 3 k) and in Sphcer. insignis 

 (pi. X, fig. 1 e) , 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 

 antennulae 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 

 Sphceronella 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 

 Sphcer. decorata (pi. VIII, fig. 3i and fig. 31). In Splicer, modesta these processes are replaced 

 by transverse lists (pi. IX, fig. 2i). 



The Antennae proceed behind, and usually at the same time somewhat obliquely 

 inside the antennulae, but never from the base of the rostrum. Sometimes they are conside- 

 rably shorter than the antennulae, sometimes about the same length, and in the genus 

 Homoeoscelis (pi. II, fig. 11 and pi. XIII, fig. lh) more than double the length. In Sphcer. 

 marginata (pi. XIII, fig. Gg) 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, oi' in other words, if the apparent basal joint consists of two joints; as, however, 

 Splicer. antiUensis has four very distinct joints (pi. Ill, 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 (pi. IX, fig. 2i and fig. 3k) comparatively broad. In Mysidion 

 (pi. XII, fig. 2h) the antennae are very small, and in Splicer, microcephala (pi. VIII, fig. 2i) 

 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 



