698 MB. w. A. qTTi!fiaKGTON ON A NEW [May 16, 



possible the metliod adopted for the distinctiou of geuera aud 

 species in its nearest allies, it may be thus diagnosed : — 



LiMNOTHELPHUSA, gen. nov. 



Carapace moderately convex, antero-lateral margins arcuated 

 and armed with spines. Trout somewhat dellexed, nearly straight, 

 and more than one-third the width of the carapace. Orbits large, 

 with prominent inner subocular tooth. Eyes large, with peduncles 

 short and stout. Second joint of antenna simple, not distorted 

 by deflexed front. Merus of external maxillipeds roughly quadri- 

 lateral, the carpus being attached towards its inner front angle. 

 Ambulatory legs considerably compressed. 



LiMNOTHBLPHUSA MACULATA, Sp. UOV. (Plate XXXVIII.) 



"Regions and sutures on carapace moderately marked. Postero- 

 lateral regions exhibiting an irregular series of small, slightly 

 oblique and granular ridges. Post-frontal crest distinct, with 

 median notch and partial lateral interruptions, but not extending 

 to margins. Antero-lateral margins shorter than postero-lateral, 

 armed with 2-3 spines, in addition to that at the outer angle of 

 the orbit. Second joint of antenna extending to under border of 

 front, and bearing a short flagellum. Chelipeds in the male un- 

 equal, subequal in the female ; merus rather short, trigonous, with 

 spine on inner margin ; carpus with two spines on inner margin. 

 Ambulatory legs rather long and slender. Colour (in spirit) hght 

 yellowish brown, with dark brown or reddish spots. 



Dimensions as follows : — 



Adult male (largest specimen) : mm. 



Length of carapace 12 



Breadth of carapace lo*4 



Length of larger cheliped about 21*7 



Length of second ambulatory leg, about 21 



Adult female : 



Length of carapace 11*5 



Breadth of cai-apace 13'6 



Length of cheliped about 12-8 



Length of second ambulatory leg, about 14-1 



While the carapace is here, as throughout the Thelphusine 

 gi'oup, broader than long, that condition is somewhat less pro- 

 nounced, giving an effect of greater squareness. The great 

 relative breadth of the front and size of the orbits are features 

 also specially noticeable, even at first sight. The prominent and 

 distinct condition of the subocular tooth (fig. 2, i.so.) seems cha- 

 racteristic, while a crenulated subocular margin forms a further 

 point of difference from other members of the group. The an- 

 tennules, with their large basal joints, are situated in the normal 

 transverse position, and the antennae occupy the interior orbital 

 hiatus. The external maxillipeds, while Thelphusine in character; 



