dr willey from the south seas. 415 



Family. Rhtnchocinetidae. 

 Genus. Rhynchocinetes H. M.-Edw., 1837. 



32. Rhynchocinetes typus H. M.-Edw., 1837. 



Rhynchocinetes typus, H. Milne-Edwards, Ann. Sci. Nat. 2 vii. p. 165, pi. iv. C. (1837). 



The single specimen, which is from Lifu, Loyalty Islands, has on the rostrum only 

 four spines above and only twelve below. 



Family. Alpheidae. 

 Genus. Alpkeinus nov. 



The recent work of Coutiere [Bull. Mus. Paris, il. p. 380 (1896)] on this family 

 necessitates the establishment of a new genus as well as of a new species for two 

 specimens of an Alpheid from Lifu. 



Characters of Alpheinus n. gen. 



1. Eyes completely covered above but not enclosed in front. 



2. Rostrum and ocular spines present. 



3. Eyestalks short, without spines above. Cornea lateral. 



4. Outer flagellum of first antenna slightly bifid at tip. 



5. Pleurobranch to each leg. Arthrobranch to third maxilliped. No epipodites. 



6. First pair of legs unequal. Left like the large leg of Alpheus, but with movable 

 finger as in Betaeus. Right small, simple. 



7. Angle of sixth abdominal segment not articulated. 



33. Alpheinus tridens n. sp., Figs. 12« — 12^. 



Diagnosis: — "An Alpheinus with the rostrum of moderate length, shorter than the 

 first joint of the antennular stalk, triangular with a sharp apex, depressed at base, 

 compressed at apex, not dentate, with a dorsal keel starting between the eyes ; ocular 

 spines resembling rostrum but shorter; carapace without other spines than the ocular 

 and with produced but not acute pterygostomial angle ; first antenna with the stalk 

 longer than the antennal scale, first joint longer than second and third together, second 

 longer than third, first two joints projecting on the outside at the distal end and 

 bearing on the projection a few strong plumose hairs; stylocerite sharp, almost equal 

 to the first joint ; second antenna with the scale shorter and the stalk longer than 

 the stalk of the first antenna, scale with strong outer border and freely projecting 

 spine, basipodite with stout spine on the outer side; third maxilliped very hairy, 

 reaching the end of the antennal scale ; larger leg of the first pair outreachiug the 

 antennal scale by the last two-thirds of the palm, hand longer than carapace, fingers 

 shorter than palm, a spine on the palm at the base of the movable finger, and a tooth 



56—2 



