( 70 ) 



6. Diogenes costatus, Henderson. Plate VI., fig. 7. 



Diogenes coitatus, Henderson, Tr. Linn. Soc, Zool., (2) V. 1893, p. 418, pi. xxxix,, 

 fig. 7, 8. 



Carapace moderately elongate, antero-lateral margins serrulate, a few 

 transverse serrulate ridges in front of the cervical groove. 



Rostrum a slender spine, shorter than the ophthalmic scales, which are 

 large and have their antero-internal angle spinulose. 



Eyestalks about four-fifths the length of the antero-lateral border of the 

 carapace, hardly reaching the base of the terminal joint of the antennular 

 peduncles, and only slightly surpassing the same point in the antennal 

 peduncles. Eyes small. 



The peduncles of the antennules exceed those of the antennae by nearly 

 half their terminal joint. Antennal flagellum a little longer than the carapace, 

 thickly setose nearly to the tip. Antennal acicle a simple spine, strongly 

 spinose along the inner edge, just reaching the base of the terminal joint of 

 the peduncle. 



Left cheliped vastly larger than the right, its length in a straight line twice 

 that of the carapace: merus a little shorter than the carpus, carpus a little 

 shorter than the palm, palm a little longer than broad, fixed finger deflexed, 

 the dactylus constituting a little more than two-thirds the total length of 

 the hand : all the borders of the merus are serrated, the two lower borders 

 strongly so ; the inner border of the carpus is strongly serrated, the spines 

 increasing in size up to the terminal one, the anterior and inferior borders 

 are also spinose, and the outer surface is beset with granules and spinules 

 except in a groove running parallel with the inner border : both borders of 

 the palm are straight, the upper border being strongly serrated, the lower 

 border being serrated only in its proximal half, and these serrations often 

 being blunted and almost worn away ; the outer surface of the palm is nearly 

 smooth, but is traversed by a ridge which, beginning at the lower proximal 

 angle, runs up parallel with the carpal articulation (where it is granular) 

 and then curves round and is continued obliquely almost to the finger-cleft. 

 The upper edge of the strongly compressed dactylus is serrated, the lower 

 edge of the fixed finger is smooth. 



The right cheliped hardly rsaches the base of the left hand ; it is granular, 

 spinose, and— especially on the hand— setose. The 2nd and 3rd legs do not 

 quite reach the end of the larger cheliped, the anterior edge of the carpus 

 and propodite is spinulose and setose, the spinules of the carpus being 

 the most distinct : the dactyli are longer than the propodites, and are 

 plumose. 



