448 ME. J. R. HENDERSON — A CONTEIBUTION 



apparently vary in length, but are usually longer tlian the peduncles. There is no 

 hepatic ridge on the carapace. The species reaches a length of about eight inches. 

 Distribution. Indian Seas, Malay Archipelago. 



271. Pen^eus affinis, Milne-Edw. 



P. affinis (Milne-Edw.), Bate, Ann. j\Iag. Nat. Hist. ser. 5, vol. viii. p. 179, pi. xii. fig. 6 (1881). 



( = ? P. monoceros, Fabr.). 



Kurachi {Brit, litis.) ; Bombay, Canara, Madras, many specimens (Day) ; common 

 at Madras (J. B. H.). 



The rostrum is straight, or only slightly sinuous, reaching the end of the antennular 

 peduncles, and continued back as a faint ridge almost to thci hind margin of the 



carapace ; the tooth-formula is -—^, the first tooth placed above the hepatic spine, and 



the second slightly behind the orbit. The antennular flagella are much shorter than the 

 peduncle. The first three pairs of legs are unispinose at the base. The fourth, fifth, 

 and sixth abdominal segments are carinated. A small sulcus is seen at the side of the 

 base of the rostrum, termed by Stimpson the gastro-froutal sulcus. The fifth pair of 

 legs in the male have a short projecting process bounding a notch near the proximal 

 end of the ischium, but this is either faintly marked or absent in young males. Pro- 

 bably this species w^ill prove to be synonymous Avith the older P. monoceros, Fabr. It 

 is much smaller than either of the foregoing species. 

 Distribution. Indian Seas, Malay Archipelago. 



272. Pen-EUS sculptilis. Heller. 



F. sculptilis (Heller), De Man, Mergui Crust, p. 286 (1888). 



( = 7-". Hardwickii, Miersj. 



Kurachi [Brit. Mm.) ; Malabar, Sunderbunds, many specimens (Dai/) ; Gulf of 

 Martaban, several specimens [Oates) ; Madras (,/. B. H.). 



The rostrum is upturned and styliform distally, varying considerably in length, but 

 usually a third or more of its length longer than the antennular peduncles, and continued 

 back as a more or less sulcate ridge almost to the hind margin of the carapace ; the 



tooth-formula is ~ , and the first two teeth are placed as in the last species. The 



antennular flagella vary considerably in length, but are usually longer than the 

 peduncles. The first and second legs are unispinose at the base. All the al)dominal 

 segments may be carinated, but the first three indistinctly so, and sometimes not jit all. 

 This species bears some resemblance to P. affinis, but is distinguished at once from the 

 latter by the presence of three crack-like marks or fissures in the integument, one 

 (which may be absent) on the edge of the pleuron of the first abdominal segment, the 

 second on the branchiostegite beiiiud the middle of the carapace, and the third on the 

 carapace, commencing above the anteunal spine and running parallel to tlie rostral ridge, 

 as far as a point beyond the middle of the carapace. In the adult male the meropoditc of 

 the fourth pair of legs is slightly dilated, but the fifth pair are not notched. 



