I. '08. 79 



the varietal name. In typical specimens of N. ensifer the 

 rostrum is very frequently fully as long as the carapace and 

 is in rare cases furnished with one or two spines on its ventral 

 horder. The third abdominal somite is prolonged into an 

 acute tooth and the pereiopods seem to be all slightly shorter, 

 the first pair reaching only to the tips of the antennal scales. 



Indian specimens (described by Alcock as A^ tenuipes) ap- 

 pear to resemble the Irish examples rather more closely. The 

 rostrum is two-thirds the length of the carapace and bears 

 about twenty-two dorsal teeth. The third abdominal somite 

 is " strongly and subacutely " produced, but the pereiopods 

 are exactly as in the form here described. Possibly tenuipes 

 will also be found worth v of retention as a varietal name. It 

 IS worth noting that Alcock describes the colour of his speci- 

 mens as bright orange, whereas the East Atlantic specimens 

 are invariably pinkish white with red appendages. 



Faxon (1895) has described an interesting feature of the 

 variation of this species off the Pacific coast of America. He 

 finds that the tvpical form occurs between lat. 0° 36' S. and 

 7° 5' X., while m specimens taken north of lat. 16° 30' N. the 

 third abdominal somite is much less produced posteriorly and 

 the rostrum bears from one to three ventral teeth. Interme- 

 diate forms are found in intermediate localities. 



The eggs attached to one of the female specimens were just 

 about to hatch, and from one of these a zoea (fig. 9) was ex- 

 tracted. The chief features of this larva are the long, sharp, 

 downwardly curved rostrum and an obtuse angle in the pos- 

 terior third of the third abdominal somite. The telson (fig. 

 10) is apically emarginate and bears seven pairs of plumose 

 setae. The mandibles, maxillae, and maxillipedes are pre- 

 sent, but no pleopods or pereiopods are developed. None of 

 the intervening stages between this zoea and the adult are yet 

 known. 



General distribution . — In the Atlantic it is known from the 

 east coast of N. America between lat. 31° 41' N. and 41° 43' N. 

 (Smith), from the Bay of Biscay (Caullery), from the neigh- 

 bourhood of Iceland (Hansen), near the Canary Is. (Sp. Bate) 

 and from the Mediterranean (Adensamer, Senna). In Indian 

 waters it has been found in the Arabian Sea and Bay of Bengal 

 (Alcock) ; and in the Pacific from the neighbourhood of the 

 Hawaiian Is. (Eathbun), from the west coasts of America be- 

 tween lat. 0° 36' S. and 27° 34' N. and from the Admiralty 

 Is. and S. of Japan (Sp. Bate). 



Irish distribution.— N. ensifer is found quite plentifully in 

 deep water off the coast of County Kerry, as the following re- 

 cords will show : — 



Helga. 



S.R. 327-8 /5/'06.— 51° 41' K, 12° 16' W. 550-800 fathoms. 

 Trawl. Temperature at 500 fathoms 9-22° C, salinity 

 35 • 167 oo— Twelve, 51-71 mm. 



