MUSEUM OF COMPAEATIVE ZOOLOGY. 215 



Aristaeus occidentalis, sp. nov. 



Similar to A. antennatus (Risso) of the Mediterranean Sea. By comparison 

 with Duvernoy's figures of A. antennatus it appears that the Pacific species 

 has a longer, more strongly upturned rostrum, and that it differs furthermore 

 in having the sixth abdominal segment carinated and toothed, and in having 

 much longer abdominal appendages. As in J., antennatus, there is no epipod 

 on either the last or the next to the last pair of legs. 



Length, 158 mm, ; rostrum, 49 mm. carapace, including rostrum, 85 mm. 



Station 3403. 384 fathoms. 1 male. 

 " 3410. 331 " 2 females. 



Hemipeneus triton, sp. nov 



This species, like H. spinidorsalis Bate, is remarkable for the long, curved 

 thorn on the dorsal side of the third abdominal segment. It differs from 

 H. spinidorsalis in having a much shorter rostrum, and longer, more flattened 

 outer antennulary flagella. The rostrum is shorter than in any previously 

 described species, being much shorter than the eyestalks ; it is furnished with 

 from two to four teeth above. The sixth abdominal somite is longer than in 

 H. spinidorsalis. Another difference between the two species affects the inner 

 branch of the second abdominal appendages of the male ; in both species this 

 branch is triple ; in H. spinidorsalis the anterior piece is a horny plate, concave 

 within and furnished with setse on its distal border ; the middle piece has the 

 form of a long triangular tooth, shorter than the anterior plate ; the posterior 

 piece is a longer multiarticulate flagellum, homologous with the inner branch 

 of the following pairs of appendages. In H. triton, the middle tooth-like 

 process is developed into a broad plate which exceeds in length the anterior 

 plate. 



Length, 127 mm. ; carapace, 44.5 mm. ; rostrum, 6 mm. 



Station 3360. 1672 fathoms. 1 female. 



3374. 1823 " 1 male, 5 females. 



" 3381. 1772 " 3 males, 1 female. 



Benthesicymus tanneri, sp. nov. 



In this species the carina on the fifth and sixth abdominal segments termi- 

 nates posteriorly in a small acute tooth, whereas in B. altus Bate these segments 

 are devoid of teeth, the posterior margin rising to form a peculiar transverse 

 ridge. B. brasiliensis Bate differs from B. tanneri in having the carapace 

 higher, with more convex infero-lateral borders, the third, fourth, and fifth 

 abdominal segments toothed, the sixth toothless, and in the absence of the 

 tooth or tubercle on the sternum between the abdominal appendages of the 



