50 



the female and the male, for not only are the antennae situated a little outside its base, but 

 the maxillulse are found (luite, or nearly quite, outside it. The general structure of the 

 mouth is like that of the adult animal; the mandibles are frequently seen in the opening, 

 but the hairs of the mouth-border are always short, frequently so short, that they can only 

 be discovered with the greatest difficulty. 



The. MaxUhd(B are difficult to understand, and it is very difficult to discover all 

 their setae. As mentioned above, in the various illustrations of the larvse I have drawn 

 what I have found, but I am pretty sure that I have not everywhere found all the elements. 

 The highest development I met in Sphcer. CaUiopii (pi. Ill, fig. 31) as well as in the species 

 which are parasitic in the marsupium of Cumacea, as Sphcpr. decorata (pi. VIII, fig. 3i), 

 (S. woffe/rt (pi. IX, fig. 21) and S. dispar (pi. IX, fig. 3 k). In these figures we see obliquely 

 behind and outside the rostrum on each side four setse, the two hindmost of which are 

 coalescent or adjacent at their base, one or both of them being plumose. Obliquely from 

 these and somewhat nearer to the rostrum proceeds a third seta, which turns straight 

 towards the front, and obliquely before this one again, there is a fourth, shorter seta. I 

 suppose that all these foiu- setae belong to one niaxillula, the basal part of which is not 

 separated from the ventral side of the head. In Spluft. marginata (pi. XIII, fig. iig) the 

 innermost seta is reduced to a short process. In most of the other forms I have only been 

 able to find tliree setae , e. g. in SpJusr. microcephala (pi. VIII, fig. 2 i) and in Choniostoma 

 mirahile (pi. XI, fig. le), or two, or only one. In Sfenothochercs egregins (pi. I, fig. 11) I have 

 found a niaxillula (e) wliich reminds me much of those in the adult animals, as it consists 

 of a short, basal part, from which proceed two tliick set<e, of which the hindmost is shortei'. 

 the foremost very long. In the genus Homoeoscelis (pi. II, fig. 1 1 and pi. XIII, fig. 1 h) I 

 have been unable to find vestiges of maxillulae. 



The MaxiUcB nearly always consist of three distinct joints, and are very much like 

 those of the adult animals, though the stout basal joint, as a rule, is narrower and the two 

 next joints are longer than in the adult; these two joints are slender, and the last one 

 somewhat curved and claw -like. In Homoeoscelis only the two last joints are entirely 

 coalescent, forming one curved joint, which moreover along the larger part of both margins 

 is provided -ftitli exceedingly fine and short setiform processes (pi. XIII, fig. 1 h). As a rule 

 all three joints are simple and smooth, but in those species of Sphceronella which live in 

 the marsupium ofCumacea, the inner margin of the third joint is coarsely or finely serrated, 

 and the first joint has on its inner margin, against which the second joint can be folded 

 up, a double row of fine cylindrical processes (pi. VIII, fig. 3n and fig. 3o), and a similar 

 decoration is seen in Sphrer. Munnopsidis (pi. X, fig. 4d). — The two maxillae are always 

 situated at some — usually at a considerable — distance from each other. 



The Maxillipeds, as a rule, are placed close behind the maxillae, and also generally 

 somewhat closer to the median line than these; in Homoeoscelis only (pi. II, fig. 11 and 

 pi. XIII, fig. Ih) there is a great distance between these two pairs of appendage^'. The 



