47 



31. Brady a dilatata, G. 0. Sars. n. sp. 



(PL XXVI). 



Specific Characters. Female. Anterior division of body considerably 

 dilated, seen dorsally, broadly oval in form, with the greatest width exceeding 

 half the length. Rostral plate well developed, narrowly rounded at the tip. 

 Urosome scarcely more than half as long as the anterior division of the body, 

 and much narrower. Caudal rami about as in B. typica. Anterior antennae com- 

 posed of only 6 articulations, the last 2 being confluent. Posterior antennae, 

 mandibles, maxillae, and posterior maxillipeds, of much the same structure as in 

 B. typica. Anterior maxillipeds, however, considerably more powerful, with the 2nd 

 basal joint fully as large as the 1st, and the apical claw remarkably strong. 

 Natatory legs rather short, with unusually broad, flattened rami. Last pair of 

 legs very small and imperfectly developed, each forming a simple setiferous lam- 

 ella, without any trace of subdivision. 



Colour whitish gray. 



Length of adult female 1.20 mm. 



Remarks, This form, though closely agreeing with B. typica in most of 

 the structural details, may be at once distinguished by the much broader form of 

 the anterior division of the body, the very powerfully developed anterior maxil- 

 lipeds, and the peculiar rudimentary condition of the last pair of legs. It also 

 grows to a considerably larger size. 



Occurrence. Only 2 female specimens of this form have hitherto come 

 under my notice. They were taken many years ago in the upper part of the 

 Christiania Fjord, in a depth of about 30 fathoms. 



Section II. Chirognatha. 



Remarks. As stated above, the forms belonging to this section are chiefly 

 characterised by the structure of the posterior maxillipeds, which, unlike those 

 in the preceding section, constitute more or less powerful prehensile organs, 

 terminating in a clawed hand. Of the 2 subsections into which it is divided, that 

 of the Dactylopoda is by far the most extensive, and I propose to treat of this 

 subsection in the first place. 



