20 Prof. J. C. Schiodte on the Structure of 



long, narrower in the fore part, with a small protuberance on 

 the outer margin, which touches the stem of the mandibles, 

 and is somewhat vaulted, but does not by any means cover in 

 the stems of the second pair of maxilla so completely as is the 

 case in ^ga. The stems of the two maxillipeds meet, as 

 in ^ga^ with their even inner margins, and likewise fit in 

 between the middle ridge of the sphenoid plate and the second 

 pair of maxillse, by means of a crest on their upper surface ; 

 but this is considerably narrower than in j3J]ga. The palpus 

 is small, pointed, biarticulate, slightly curved inwards, with a 

 row of small hooked spines on the inner or lower edge of the 

 terminal joint. The upper or outer margin of the palpus is 

 also in Cymothoa arranged to fit into a groove in the stem of 

 the mandible, and forms the side margins of the mouth-tube. 



In the female, on the contrary, the maxillipeds are con- 

 verted into a pair of thin lamellse, which are almost entirely 

 covered from beneath by the first pair of plates of the egg-bag, 

 and which do not reach so far that the palj^i can form part of 

 the mouth -tube ; the cardo, besides, has a foliaceous inward- 

 turned prolongation ; and, as the inner margins of the stems, 

 moreover, are not quite rectilinear, the stems do not meet ac- 

 curately along the middle line of the skull, and it is only on 

 a short piece that they fit in above between the ridge of the 

 sphenoid plate and the second pair of maxillse. Each of the 

 stems, besides, expands on the outer side into a large, thin, 

 rounded leaf, which reaches forward a considerable distance 

 beyond the small palpus, of which only the last joint has a 

 few thorns at the apex. 



In both sexes the maxillipeds are without lobes : the inner 

 corner of the stems certainly presents a little eminence, which 

 is jDarticularly easily observed in the male ; but it lacks setae, 

 and can consequently hardly be looked upon as a lobe. 



Of course this great sexual difference in the structure of the 

 mouth entails a corresponding difference in the part taken by 

 the maxillae of the second pair in the composition of the mouth- 

 tube. 



The peculiarity of the second 'pair of maxillce in Cymothoa 

 consists in this, that the lobes are neither separate lobules as 

 in JEga, nor turned back in the shape of collars, but they 

 coalesce with one another, are soft, swelling, and by slight 

 longitudinal grooves divided into small oval cushions (three 

 on each maxilla), which together form the posterior part of the 

 orifice of the mouth-tube. The outermost cushion has on the 

 outside and at the apex a scattered number of small pointed 

 warts ; the intermediate and innermost cushions liave no 

 warts except on the margins, but have besides in their fore 



