1902. J CRUSTACEA OF THE " SKEAT EXrEDITIOX." 377 



pieces, of which the distal (tergal) broadens to the blunt distal 

 end. 



Affinities. — This species is certainly closely allied to Dichelaspis 

 ivarivickii Gray. The general external appeai'ance is much the 

 same, making allowance for its variability in this species, and the 

 mouth-pai-ts appear to agree essentially with the description of 

 Z>. warwickii given by Darwin (Lep. pp. 121-122). But it 

 differs in the fact that the valves are not thin and translucent, 

 but thick and opaque ; in the distal broadening, and division into 

 two parts, of the carina ; in the shape of the tergum (despite its 

 variability) ; and in the fact that the 1st cirrus is not " far 

 removed from the 2nd," and that the rami of the 2nd are not 

 unequal, 



Althoiigh the shape and fission of the carina is the most 

 constant external feature, I have found it dilficult to fix that fact 

 satisfactorily in the specific name ; words such as bicai'inata, Jissi- 

 carinata, or others suggesting rather a reduplication of the carina 

 than a single carina formed of two pieces. 



I have, therefore, fixed on the horse-like shape of the tergum, 

 which, though not constant, still evidently represents the typical 

 form of that valve in the species, by which to designate the 

 species ; hence the specific name equina. 



0. ISOPODA. 

 XYI. Genus Oymothoa Fabr. 



30. Oymothoa .stromatei Bleeker. 



Cymothoa stromatei Blkr. Act. Soc. Sci. Indo-Neerland. ii. p. 35, 

 pi. ii. fig. 13 (1857). 



Iioc. ? Hab. " Mouth-parts of fish, chiefly of Ikan dalam." 



Six females and a small male. 



31. Cymothoa pulchrum, sp. nov. (Plate XXXY. figs. 8-8 a.) 



Log. Pulau Bidan. One female. 



Eyes invisible, lateral prolongations of the 1st thoracic segment 

 reaching very nearly to the level of the front, which is rounded 

 acuminate. Oephalic segment | as long as broad (4'5 : 6 mm.), 

 superiorly depressed so as to form a shallow pit ; 1st thoracic 

 segment the longest, 2nd, 3rd, and 4th a little shorter and sub- 

 equal, 5th, 6th, and 7th gradually becoming shorter, the 5th not 

 abruptly shorter than the 4th ; segments 1-6 rugose, the rugosities 

 becoming gradually less marked on the hinder segments, the 7th 

 smooth ; the lateral prolongations of the 1st segment smooth, 

 curved forwards and inwards, bluntly pointed in front. Abdomen 

 abruptly naiTOwer than thorax, the segments gradually increasing 

 in width to the 5th, which is as wide as the last thoracic, and the 

 6th, which is as wide as the penultimate thoracic, segments. 6th 

 abdominal segment about twice as wide as long (15 : 7 mm.), 

 somewhat excavate in the anterioi- median line, and slightly 



