REPOKT ON THE CRUSTACEA MACRTJRA. 



503 



Habitat.— Station 208, January 17, 1875; lat. 11° 37' N., long. 123° 31' K; 

 off Manila; depth, 18 fathoms ; bottom, blue mud. Two specimens ; females, one with 

 ova. Trawled. 



Observations. — This species, which comes from the same station as Alpheus spiniger, 

 corresponds very closely with Stimpson's description of Alpheus biunguiculatus. 

 According to that author it differs from Alpheus neptunus in having no spine on the 

 palm at the base of the fingers in the larger hand (" manus majoris palma spina ad 

 basin digitorum armata"). In the two specimens in this collection the larger hand is 

 wanting. Dana does not figure any such spine, neither does he allude to it in his 

 description, and he also figures his species Alpheus neptunus as having the dactylos of 

 the third and following pairs uniunguiculate, whereas Stimpson says that it is 

 biunguiculate. Had Dana figured the fifth or last pair as being so formed, we might 

 have supposed that he overlooked that of the third and fourth pairs ; for frequently, if 

 not always, when the dactylos of the third and fourth pair is Particulate, that on the 

 fifth is single ; but as he figures the third pair we cannot suppose him to have been 

 incorrect. I therefore attribute our specimens to Stimpson's species Alpheus 

 biunguiculatus. 



This species corresponds with Heller's description of Alpheus charon, which was 

 procured off the Nicobar Islands, and of which he says that " this species possesses on 

 the frontal margin three pointed, spine-like processes, the central one of which is some- 

 what the longest, and reaches as far as the anterior end of the first joint of the first 

 antennse. On the last three pairs of pereiopoda the chela is very short and furnished 

 with a double claw. In most other points this species corresponds closely with 

 Alpheus neptunus." I have thus been induced to associate them as the same species. 



Alpheus neptunus, Dana (PI. CI. fig. 2). 



Alpheus neptunus, Dana, U.S. Explor. Exped., Crust., vol. i. p. 553, pi. xxxv. fig. 5. 

 „ „ Stimpson, Proc. Acad. Nat. Sci. Philad., p. 100, January 1860. 



Anterior margin of the carapace anteriorly produced to a short sharp-pointed 

 rostrum. Orbital margins anteriorly produced into a long tooth over each ophthalinopod, 

 and subequal with the rostrum. 



