1922.] 



S. Kemp : Notes on Crustacea Decapoda. 



145 



extend to the tip, the second being above or slightly behind the 

 posterior limit of the orbit. The lower border of the rostrum bears 

 r, rarely 2 teeth 1 which are rather larger than those of P. indicus 

 and occupy a different position. In P. indicus there are as a rule 

 2 very small teeth, the hindmost of which is placed below or in 

 advance of the foremost tooth of the dorsal series, whereas the 

 single tooth usually found in P. obscurus is placed much further 

 back, with at least one, often with two or three dorsal teeth in 

 advance of it. 



In the antennules and antennae there is little difference 

 between the two species, but in P. obscttrus the antennal scale (text- 

 fig. 14c) is rather less parallel-sided than in P. indicus and the 



Text-fig 



14. — Periclimenes obscurus, sp. now 



a. Anterior part of carapace of male. 



b. The same parts of female. 



c. Antennal scale. 



fused portion of the outer autennular flagellum is shorter and 

 composed of only 4 or 5 segments. 



The moUth-parts, maxillipeds and first peraeopods do not 

 exhibit any distinctions worthy of note. The second peraeopods 

 are often a little unequal and show much variation in the propor- 

 tionate lengths of the segments. As in P. indicus they are unarmed. 

 Jn ovigerous females (text-fig. 156) the carpus is slightly shorter 

 than, as long as, or rather longer than the palm. In males (text- 

 fig. 15a) it is sometimes longer than the palm, rarely shorter than 

 it, while young individuals not infrequently resemble P. indicus 

 in having the carpus as long as the chela. The fingers are as a 

 rule clearly shorter than the palm, thus differing from those of 

 P. indicus which are always fully as long as the palm. In young 

 specimens, however, and rarely in full-grown females the dactylus 



1 Of thirty-three specimens thirty-one have a single ventral tooth and two 

 have 2 ventral teeth. 



