300 Prof. J. C. Schiodte on the 



carry a row of tactile setge. In consequence of these circum- 

 stances, both pairs of maxillae are uncovered unless the palpi 

 of the maxillipeds happen to be in an inward-bent position, in 

 which case they can cover the outer portions of the first pair 

 of maxillaj and also the dorsal margin of tlie mandibles, wliich 

 appear behind their outer lobes. The maxillae of both pairs 

 being thus uncovered, it devolves on them to cover the hypo- 

 stoma, which is otherwise mostly done by the lobes of the 

 maxillipeds; and accordingly the second pair of maxillae 

 assume an aspect which reminds us in a high degTce of the 

 maxillipeds in Isopoda. Their stipites coalesce entirely, 

 forming an obovate flatly arched piece, which covers the 

 hindmost part of the hypostoma in tlie middle, from the 

 cleft between the stipites of the maxillipeds forward to the 

 bases of the lobes of the first pair of maxillse. The inner 

 lobes of the second pair are placed close together in the 

 median line of the head ; and their rounded apices carry each 

 one stout tactile seta : the outer lobes are small, triangular, 

 and inserted on a level with the narrow bases of the inner 

 lobes ; and their rounded apices cany two rows of more slender 

 tactile setge — one row on the upper surface, the other on the 

 edge. The apices of all the lobes of the second pair of 

 maxillas reach forward as far as the middle of the inner 

 margin of the outer lobes of the first pair of maxillee, and a 

 little beyond the base of the lower lip ; the second pair of 

 maxillge therefore cover altogether only a small space in the 

 middle of the hypostoma, but leave the maxillae of the first 

 pair entirely uncovered. The covering of the hypostoma on 

 the sides towards the pleural margin of the head, devolves 

 consequently on the first pair of maxillae, which to this end 

 are equipped with cardines of enormous size, much larger than 

 are necessary for the purpose of the articulation of the limb, 

 being expanded outwards from the sockets into a pair of 

 obovate flatly convex plates, placed aslant, each of which is 

 divided a little behind the middle into two halves by a 

 curved transverse groove on the lower face, corresponding to 

 a ridge in the interior, on which the flexor muscles are 

 attached ; the stipites of this first pair of maxillse are, for the 

 same reason, of unusual width. There is no inner lobe ; but 

 the outer lobe is broad, along the inner margin armed with 

 small hooked setae, whilst the obliquely truncate apex carries 

 seven stout, deeply inserted, conic, slightly incurved spines, 

 which have a prominent serrate ridge on their lower surface, 

 a little inside the inner margin ; the spines form two rows, 

 the upper row consisting of four, the lower of three spines* 

 The very short and slender palpus consists of only one conic 



