1904.] ASELLOTA-GROUP OF CRUSTACEANS. 323 



Remarks. This deep-sea species is the largest form of the genus 

 hitherto known ; it is easily distinguished from all other species 

 by the very lai-ge lateral processes of the head, the shape of the 

 eyes, of the basal joint of antenna?, and of the first thoracic legs. 



5. Stenetrium serratum, sp. n. Ovigerous female. (Plate XIX. 

 figs. 3 «-3 d ; Plate XX. fig. 1 a.) 



Head has its upper surface (the frontal plate excluded) neai-ly 

 twice as broad as long ; the lateral part is somewhat expanded 

 and flattened in front, and produced into a moderately large acute 

 process ; the front margin outside the base of each antennula 

 produced into a rather large process, which is broad at the base, 

 while its distal part is shaped as a narrow acute hook curved 

 somewhat inward. Eyes large, oblong, very oblique, the outer 

 margin extremely convex, the inner very concave ; their posterioi- 

 part overlaps the lateral margin of the head itself. 



Antennulfe have the second joint of the peduncle moderately 

 robust and somewhat shorter than the third ; flagellum 9-jointed, 

 as long as the sum of the two proximal joints of the peduncle. 



Antenna? have the basal joint, seen from above, distally cut ofi' 

 transversely, its outer angle acute, but not produced into any 

 process. 



First thoracic legs i-ather short. Third joint distally widened 

 but without process ; fourth joint with the vipper part nearly 

 from the base strongly expanded, compressed and distally pro- 

 duced into a process of moderate length and bi-eadth ; fifth joint 

 similai'ly expanded and distally produced into a long slender 

 process. Hand a little more than twice as long as deep ; upper 

 margin rather feebly convex, with a few seta? ; lower margin 

 straight, only half as long as the upper, with numerous very long 

 hairs ; distal end as long as the lower margin ; palmar edge very 

 oblique, a little sinuate, furnished with six very stiff setfe, pro- 

 portionately long and increasing in length downwards, pectinate 

 along their upper mai-gin, and at the end of the edge a moderately 

 robust very long spine pectinate as the seta? ; the angle between 

 palmar edge and lower margin measures about 130°. Seventh 

 joint with its claw claw-shaped, reaching a little beyond the lower 

 end of the palmar edge ; the joint is adorned below with serrated 

 spines and fine curved seta? as in S. mediterraneimi, but the spines 

 are less numei-ous, only about ten. 



Abdominal shield is somewhat broader than long ; each lateral 

 margin is adorned with five small nearly spinifoi-m processes, 

 increasing in size backwards and placed at regular intervals, the 

 last of these processes being that at the usual iiotch. Posteiioi- 

 mai'gin is rather evenly but moderately curved. 



Uropoda wanting. 



Length of the single adult female 6 mm. 



Occurrence. West Indies : St. Thomas, one specimen {Krebs). 



Remarks. This species is easily distinguished from A', armattwi, 

 /S', fractu7)i, and *S'. mediterranewm by the , absence of a process 



21* 



