176 



examining his type specimens, that both are founded only upon young speci- 

 mens of the present species. 



Occurrence. The species would seem to be a genuine arctic form, 

 occurring rather plentifully oft the whole coast of Nordland and Finmark, in 

 moderate depths, but also occasionally extending southwards along the west 

 coast of Norway, at least to Bergen. 



Distribution. Arctic Ocean, widely distributed: Greenland, Labra- 

 dor, Iceland, Spitsbergen, the Murman Coast, the Kara Sea, the Siberian 

 Polar Sea; east coast of North America (Stimpson), '? Bohuslan (Lilljeborg). 



9. Ampelisca odontoplax. U. o. Sars. 



(PI. 61, fig. 2). 

 Ampelisca odontoplax, G. 0. Sars, Crust. & Pygnog. nova etc. No. 31. 



Cephalon exceeding in length the 3 anterior segments of mesosome 

 combined, distinctly keeled dorsally, and but slightly tapering distally, tip 

 transversely truncated, and emarginated in the middle. The 3 anterior pairs 

 of coxal plates rather narrow, and turned obliquely forwards, each with a 

 very distinct dentiform projection at the infero-posteal corner; 1st pair but 

 very slightly expanded distally, and scarcely broader than the 2 succeeding 

 pairs; 4th pair fully as broad as it is deep, inferior and posterior edges forming 

 an even uninterrupted curve. Metasome distinctly keeled dorsally, last pair 

 of epimeral plates produced at the lateral corners to a rather short dentiform 

 projection. First segment of urosome with a slight dorsal carina terminating 

 with a sharp corner. Eyes wholly absent. Superior antennae of female about 

 half the length of the body, 1st joint of the peduncle rather large, 2nd twice 

 its length, and much more slender, flagellum scarcely twice the length of the 

 peduncle, and composed of about 32 articulations. Inferior antennae not quite 

 twice as long as the superior, last joint of the peduncle shorter than the 

 penultimate one. Gnathopoda nearly as in A. Erchrichtii. Dactylus of the 

 anterior pairs of pereiopoda very slender, and considerably exceeding the length 

 of the 2 preceding joints combined. Last pair of pereiopoda rather strong, basal 

 joint very broad, but scarcely as long as the remaining part of the leg, posterior 

 expansion nearly trans versely truncated at the tip; the 3 succeeding joints 

 about as in A. Erchrichtii, propodal joint, on the other hand, considerably 

 larger, oblong in form, and exceeding in length the 2 preceding joints combined, 

 dactylus about half its length, and narrowly lanceolate. Last pair of uropoda 

 about as in A. Exchn'chtii; penultimate pair witli both rami densely spinous 

 on the inner edge, the outer spine in each much longer than the others. 

 Telson oblong oval, with 2 pairs of dorsal denticles, tip of the terminal lobes 



