16 



2. Glabrous, upper edge of free portion of rostrum with 12 or 13 

 teeth s lobes of copnlant organ of first pair of male abdominal 

 appendages equal ... ... ... P. rectacntus. 



II. Rostrum in both sexes less than half the length of the rest of the 

 carapace measured in the mid-dorsal line : a fine fissure traverses the 

 carapace longitudinally, on either side, from a point just inside the 

 antennal spine, to the posterior border ... ... ... P. investigatoris. 



l. Pencils (Metapeneus) coniger, Wood-Mason. 



llelapeneu* coniger, Wood-Mason, Ann. Mag. Nat. Hist., October, 1891, p. 272. 

 ILLUSTRATIONS or THE ZOOLOGY OF THE INVESTIGATOB, CRUSTACEA, PT.ATE L. FIGS. 2, 2a, 2b. 



Tomentose. Rostrum with a faint double curve, armed dorsally with 6 or 

 7 teeth in addition to a tooth on its gastric carina : in the female its free portion 

 is over three-quarters the length of the rest of the carapace measured in the 

 mid-dorsal line, and its tip reaches well beyond the far end of the antennular 

 peduncle, but in the male its tip falls short of the end of the antennular 

 peduncle : the rostrum is produced backwards as a distinct carina only in the 

 anterior half of the carapace. Cervical groove indistinct. 



Abdominal terga, from the 2nd to the end of the 6th, with a median carina, 

 indistinct and incomplete on the 2nd, increasingly sharp and distinct to the 6th, 

 where it ends in a spine. The 4th, 5th, and 6th terga are distinctly subcarinate 

 on either side of the median carina. 6th somite at least twice the length of the 

 5th. Telson a good deal shorter than the endopodite of the caudal swimmeret, 

 slender, acute, armed on either side in its posterior half with four spines the last 

 of which alone is fixed. 



Eyes large. Inner antennular flagelluin hardly as long as the antennular 

 peduncle, much longer than the outer flagellum : in the male only, the inner- 

 upper border of the base of the inner flagellum is slightly concave up to a small 

 denticle. Antennal scale as long as the rostrum in the male, but not quite as 

 long in the female. 



Second joint of the mandibular palp (endopodite) tomentose, nearly as 

 broad as long. 



There is a spine at the far end of the-'basis and ischium of the first pair of 

 thoracic legs. Between the 2nd pair of thoracic legs, in the female, is a pair of 

 small sternal teeth. 



The posterior border of the " thelycum " is not undermined and is curved 

 like a <a reversed, the middle limb of the <a being very short and narrow. 



The " andricum " of the first pair of abdominal appendages is about a third 

 as long as the carapace (without the rostrum), and is strongly calcified at tip : 

 its left lobe, which is folded round a tubular spiral process of the right lobe, is 

 longer than the right lobe. 



