Cumacea: 9. Leuconidae, 1. Leucon 73 



lobe carrying a series of 3 denticles close to each lateral fissure. Fedigerous 

 segments 1 — 5 with laminar sideplates slightly projecting laterally. Telsonic 

 segment pentagonal, produced end apically rounded. Antenna 1, 2°*^ joint a 

 little shorter than 1«*, and 3^ than 2"'^, flagellum 3-jointed, 1^* joint twice 

 as long as 2^^ and 3^ combined, accessory wart-like. Maxilliped 1, with 5 

 branchial sacs, the membranous exopod elongate. Peraeopod 1, 5*^ and 6*^^ 

 joints subequal, 7*^ much shorter than either, apically carrying some half 

 dozen strong, claw^-like spines. Peraeopod 2 with 3*^ joint wanting or fused. 

 Peraeopod 3 in young d apparently without any peculiar appendages on 3*^ 

 joint, but seemingly in both sexes the 5**^ joint carries 3 strong setae, the 

 distal part of which is densely annulated and apically uncinate. Peraeopod 5 

 alike in both sexes, and very small. Peduncle of uropods as long as the 

 endopod, in which the 1^* joint is a little more than twice the second, fringed 

 on medial margin with a dozen spines, 3 conspicuously larger than the rest; 

 the 2*1^* joint has 5 medial marginal and 2 larger apical spines; the exopod 

 is about a fifth of its length longer than the endopod. Colour light yel- 

 lowish. L. Q and young d, 9 mm. 



Kerguelen, Cumberland Bay, depth 232 m. 



18. L. acutirostris 0. Sars 1865 L. a., G. 0. Sars in: Forh. Selsk. Christian., 

 1864 p. 181 I 1894 L. a.., A.M.Norman in: Ann. nat. Hist., ser. 6 ?;. 13 p. 275 | 1900 

 L. a., G. O. Sars, Crust. Norway, v.3 p. 34 t. 26 | 1900 L. a., Zimmer in: Fauna arctica, 

 v.l p. 432, 438, 439, 444 | 1908 L. a., Zimmer in: Erg:eb. Tiefsee-Exp., v.8 p. 178 | 1911 

 L. a., Stappers in: Camp. arct. Orleans, Crust. Malac. p. 107 t. 4 f. 10. 



Body of 9 rather short and thick, of d more slender. Pseudorostral 

 lobes rather short, especially in d, horizontal, acuminate, margins adjacent 

 to apex denticulate, setiferous; antero-lateral corners acutely produced in g 

 with serration following a narrow sinus, blunt and smooth in d; lower margin 

 serrate for some distance in both sexes. Median carina on anterior half of 

 carapace in 9, strongly denticulate, but entirely wanting in d. Telsonic 

 segment pentagonal, produced part apically rounded. Peraeopod 1, 5^^ and 

 e*'^ joints equal, 7^^ much shorter, apically setose. Peraeopod 2 without 8*^ 

 joint. Peraeopod 3 of d having 3 lanceolate not distally denticulate append- 

 ages on the 3*^ joint. Peduncle of uropods equal to endopod, in which the 

 2^^ joint is two-thirds of the V^ in 9 , a little over half in the d, having 



4 spines on medial margin of each joint in 9, but in d 12 on 1*^ and 

 6 on 2^^, with a long apical spine in both sexes; exopod somewhat longer 

 than endopod. Colour whitish with olive tinge. L. 9 3 mm, d 3*5 mm. 



Coast of Norway, depths 56 — 548 m; Nova Zembla, 90 m. 



19. L. sagitta Zimmer 1907 L. s., Zimmer in: Zool. Anz., v. 31 p. 225 | 1909 

 L. s., Zimmer in: Ergeb. Schwed. Siidpol.-Exp., v.6 nr. 3 p. 7 t. 2 f. 17 — 81. 



Body slenderly lanceolate. Pseudorostral lobes moderately long, slightly 

 upturned, apically acute, the oblique margins feebly denticulate; antero-lateral 

 corners triangular, under margin of carapace denticulate for a space. Median 

 carina of carapace reaching to middle or further, with teeth varying from 5 

 to 12, with sometimes a single tooth near the hind margin. Pleon segment 



5 rather short. Telsonic segment with produced part almost truncate but 

 not sharply. Eyelobe reduced to a little point. Antenna 1, accessory flagellum 

 about three-fourths as long as 1^* joint of the principal. Peraeopod 1, 7^^ 

 joint nearly as long as 6**\ 6*^ much shorter than 5*'^ Peraeopod 2 with 

 3^ joint lost or fused, and this joint not very clearly separated from the 2^^^ 



