CEUSTACEA OF THE MERGUI AECHIPELAaO. 71 



most as only a subgenus of NejJtumis. Hitlierto four species of 

 the subgenus Sellenus and three of XipJionectes were known as 

 inhabitants of the Indo-Malayan seas. 



Neptuniis Andersoni in its outer form and physiognomy 

 appears closely allied to Neptumis {Eellemts) rugosus, A. Milne- 

 Edw., from Australia; but it is distinguished by the arms of 

 the chelipedes not bearing one but two spines It also greatly 

 resembles Hfeptunus {Sellenus) hastcitoides ; but N. Andersoni 

 presents a much broader frontorbital margin in proportion to the 

 length of the carapace, and the arms of the chelipedes project 

 less beyond the antero-lateral margins of the cephalothorax than 

 in that species. 



The upper surface of the carapace appears extremely uneven, 

 as in N. rugosus, for it is not only very much embossed, but 

 many lobules even rise into more or less developed, slightly 

 granulated tubercles. Two slightly elevated tubercles are found 

 on each protogastric lobe, and a somewhat larger tubercle is 

 placed on the mesogastric lobe; behind the latter, two tubercles 

 are observed on the cardiac region, placed iu a transverse line 

 close together, and more elevated than all the others. A single 

 median tubercle occupies the middle of the intestinal region, 

 and finally some other tubercles are placed symmetrically on the 

 postero -lateral regions of the carapace. The whole surface is, 

 moreover, covered with a short dense down, which, however, 

 does not conceal the tubercles. 



As in N. rugosus, the frontorbital or anterior margin of the 

 carapace is comparatively very broad in proportion to the length , 

 the latter being nearly as long as the distance between the ex- 

 ternal orbital angles. Unfortunately the left half of the frontal 

 margin of our specimen is a little mutilated, so that I cannot 

 describe exactly the form of the median tooth or teeth of the 

 front ; for, as in N. rugosus, a single small median tooth may 

 perhaps also be found in this species in the middle of the front, 

 or there may be two very small teeth. Iu every case the median 

 tooth or teeth are much smaller and project much less forward 

 than the next teeth ; the latter are triangular, a little acute, and 

 project about as much forward as the epistome, but not so much 

 as the. internal lobe of the under orbital margin. These teeth 

 are separated by a rather deep emargination from the small, 

 obtuse, external angles of the front (internal orbital angles), 

 which project still less forward than the median tooth. 



