368 t>E. W. T, CALMAN ON NEW OE RARE 



1?. Exopods preseut on third and fourth legs of male. 



a. Carapace with numerous longitudinal ridges C casta ta. sp. n. 



b. Carapace with a pair of dorso-lateral ridges G. bicristata, sp. n. 



Gynodiastylis carinata, sp. n. (Plate XXXV. figs. 6-31.) 



Description of adult Female. — Total length 40 mm. 



Carapace a little less than one-third of total length, its vertical height a little more 

 than one-half of its length, subcylindrical, narrowed in front ; dorsal outline very 

 slightly arched as seen from the side. Pseudorostrum straight, horizontal, acutely 

 pointed, a little less than one-fourth of length of carapace. Antennal notch widely 

 open, defined below by the slightly-produced antero-lateral tooth. The surface of the 

 carapace bears six longitudinal ridges on each side. Starting from the hind margin 

 near the middle line, a ridge, somewhat less strongly marked than the others, runs 

 forwards and inwards to meet its fellow at about the middle of the length of the 

 carapace; from nearly the same point on the hind margin the second ridge runs 

 directly forwards as far as the ocular lobe ; the third ridge, nearly parallel with the 

 last, curves slightly inwards anteriorly and ends close to the fronto-lateral fissure ; 

 the fourth ridge curves upwards a little in front of its origin, bounding a shallow 

 depression on the side of the carapace, and then runs iorwards on to the base of the 

 pseudorostrum ; the fifth ridge, which is very strong, runs below the above-mentioned 

 depression and ends on the antero-lateral angle ; a faintly-marked sixth ridge is visible 

 in some specimens just above the lower margin of the carapace. The ocular lobe is 

 less than twice as broad as long and bears three large but indistinctly defined corneal 

 facets ; the eye is without pigment. 



All the five leg-bearing somites are distinct. The pleural plates of the third somite 

 are expanded and produced in front and behind and the corresponding appendages are 

 articulated near the posterior end, so that, in the adult female, a wide interval is left 

 between the second and third pairs of legs. In this somite also, and to a greater 

 degree in the two succeeding somites, the attachment of the limb is rotated backwards 

 and upwards, so that, in the last somite, the leg is attached to its posterior border, and, 

 when extended, points directly backwards. The last two somites have each a pair of 

 longitudinal ridges on the dorsal surface. 



The abdomen is distinctly shorter than the cephalothoracic region ; the somites are 

 slightly depressed, Avith a lateral longitudinal ridge on each side : as is usual in the 

 Diastylidae, the hinder edge of each somite is strongly concave on the upper surface. 

 The penultimate somite is little longer than the preceding. The last somite is 

 flattened from above downwards and is about as broad as long. 



The telson is two-thirds as long as the last somite. Seen from above it is ovate in 

 outline, its breadth three-fourths of its length, truncated in front and bluntly pointed 



