100 Cumacea: 11. Diastylidae, 1. Diastylis 



and 4**1 pairs stoutly built, without exopods in Q. Peduncle of uropods 

 longer than the telson. exopod scarcely half as long as the peduncle, very 

 little longer than the endopod, of which the P^ joint is nearly double the 

 2"d and 3^ combined, with 9 spines on the medial margin, the 2"^^ having 2, 

 the 3^ none and its apical spine not separate from the joint. Colour whitish. 

 L. 25—35 mm. 



Coasts of N. Europe, Atlantic coast S. of Labrador, Polar Islands of N. America, 

 Greenland, Jan Mayen, Spitzbergen, Barents Sea, Kara Sea, Siberian Polar Sea. southward 

 reaching lat. U^ U5' 30" N., long. SB" 31' 30" W., depths 2—377 m. 



19. D. Stygius 0. Sars 1871 D. stygia, G. O. Sars in: Ofv. Ak. Forh., v. 28 nr. 6 

 p. 798 I 1873 D.S., G. 0. Sarsin: Svenska Ak. Handl., n. ser. r. 11 nr.6 p. H t. 2 f.4 — 7 

 1879 D. s., A. M. Norman in: Ann. nat. Hist., ser. 5 v. 3 p. 57, .^8 | 1886 D. s., G. 0. 

 Sars in: Norske Nordhavs-Exp., v. 6 nr. 15 p. 22 | 1887 D. s., G. 0. Sars in: Rep. Voy. 

 Challenger, v. 19 pars 55 p. 44 t. 6—8 | 1900 D. s., Zimraer in: Fauna arctica, v. 1 p. 425, 

 434 I 1901 D.polaris, Ohlin in: Bib. Svonska Ak., d. 26 nr. 12 p. 50 | 1912 J>. stygia. 

 Caiman in: P. U, S. Mus., u41 p. 605, 661. 



Very near to D. polaris (nr. 20). Pseudorostral lol)es conically pro- 

 duced, horizontal, antero-lateral corners obsolete; carapace with lower margin 

 serrate anteriorly, surface in g beset with small spinules, densest in front, 

 but only scantily represented in the 6, which on the other hand has a 

 pair of anterior lobes with serrate edges and a lateral keel low down on each 

 branchial region. Pedigerous segments 1—3 and 5 have the front margin 

 finely denticulate, 2—4 in the $ are firmly connected, 1—3 have a medio- 

 venti-al ridge, postero-lateral angles of the 5*^ acutely produced and carrying 

 4 plumose setae in the cS, but not acute in the 9, which has 2 small dorsal 

 denticles, while in the 6 it has a ventral serrate crest, which is continued 

 on the first 2 pleon segments, pleon segments 1 — 6 otherwise smooth in 

 both sexes, or 1^* in 9 with a ventral spine (A. M. Norman); telson about 

 twice as long as 6*^ pleon segment with 9 pairs of lateral spinules in 9, 

 thrice as long, with 15 pairs of spinules in the d. Eyelobe small, eye wanting. 

 Antenna 19,1^* joint much longer than 2"^^ and '6^ combined, 2"'^ a little 

 shorter than 3^. Antenna 2 6, fiagellum very long. Peraeopod 1, 2°^ joint 

 spinose and setose, not so long as rest of limb, 5^^ to 7^^ joints subequal. 

 Peraeopod 2, 3"^ joint with a strong denticle, 4^''^ with 2 such denticles, 7^^' 

 joint a little longer than G**i, 5*^^ much longer than both combined. 3'^ and 

 4*'! pairs without exopods in the 9 . Pedimcle of uropods rather longer than 

 the telson, not quite twice as long as the subequal rami; P^ joint of endopod 

 longer than the 2"^ and 3* combined, spines on the 3 joints respectively 8. 

 4, 3 in 9, 13, 9, 5 in d. L. 9 16 mm, d 21 mm. 



Atlantic coast of N. America south of Labrador, depth at a single station 267 ni, 

 otherwise only at depths varying between 1134 and 4896 ni (or at most 3200, Ohlin). 



20. D. polaris 0. Sars 1871 D. jj.. G. O. Sars in: Ofv. Ak. Forh., u 28 nr. 6 

 p. 797 I 1873 D. p., G. O. Sars in: Svenska Ak. Handl., n. ser. u U nr.6 p. 4 1. 1 f. 1 — 3 

 1879 D. p., A. M. Norman in: Ann. nat. Hist., ser. 5 i'. 3 p. 56 | 1886 Z>. ja, G. O. Sars 

 in: Norske Nordhavs-Exp., u6 nr. 15 p. 22 | 1900 D. p., Ziramerin: Fauna arctica, v. I 

 p. 423, 434 I 1901 D. j)., Ohlin in: Bih. Svenska Ak., v. 26 nr. 12 p. 50. 



Pseudorostral lobes shortly conical, horizontal, antero-lateral corners obso- 

 lete; dorsal line of carapace nearly straight, surface beset with very small 

 forward pointing denticles, sides having 1 or 3 (G. 0. Sars) or 2 (A. M. 

 Norman) very indistinct obliquely transverse pleats or wrinkles, lateral margin 



