Axelboeckia 391 



14. Gen. Axelboeckia Stebb. 



1894 ßoeckia (Sp. un. : ß. spinosa) (non A. W. Malm 1871 !), (O. Grimm in MS.) 

 G. C). Sars in: Bull. Ac. St.-Petersb., ser. 5 v.l \). 182 | 1899 Axelboeckia, T. Stebbing 

 in: Tr. Linn. Soc. London, ser. 2 v.l p. 423. 



Integument crustaceous, body robust, witli median and marginal carinae, 

 pleon Segments 5 and 6 small. Head rostrato. Side-plates 1 and 4 shorter 

 than 2^ or 3*^. 4*'' not veiy broad, nor much emarginate behind. Antenna 1 

 the longer, with accessoiy flagellum. Mouth-parts nearly as in Gammarus 

 (p. 460), but apex of npper lip scarcely emarginate, lower lip with broad 

 principal lobes separated by rudiments of inner lobes. Maxiila 1 on right 

 has apex of palp expanded. denticulate, on left narrower, with a few 

 slender spines. Maxillipeds, 3^ Joint of palp distally expanded. Gnathopods 

 1 and 2 nearly alike, small, subchelate, sti'onger in ö than in 9 . Peraeopods 

 1 — 5 differing little in length. Peraeopods 3 and 4, 2* Joint narrow. 

 Peraeopod 5, 2* Joint broadly expanded. Branchial vesicles broad, with 

 narrow attachment, üropods 1 — 3 successively smaller. üropod 3 short, peduncle 

 Short, outer ramus 1-jointod, inner shorter. Telson very small, unarmed, not 

 deeply cleft. 



2 species. 



Synopsis of species: 



Antenna 1, accessory flagellum 1-jointed 1. A. spinosa . . p. 391 



Antenna 1, accessory flagellum with more than 1 Joint . . 2. A. carpenterii . p. 392 



1. A. spinosa (O. Sars) 1894 Boeckia s. (B. nasuta, B. hystrix), (0. Grimm 

 in MS.) G. 0. Sarsin: Bull. Ac. Sl.-Petersb., ser. 5 v.l p.l83 1. 1, 2 | IS%^ Axelboeckia s., 

 T. Stebbing in : Tr. Linn. Soc. London, ser. 2 v.l p. 424. 



Body extremely stout in 9 , less so in d . Back obtusely carinate 

 throughout, peraeon segments each with spiniform process on each side near 

 side-plates, in segment 5 very large, acute, the others smaller and rather 

 obtuse; pleon segments 1 — 4 with a pair of subdorsal, upturned processes, 

 segment 4 overlappiug 5"' and 6*^^ and ending in a rather large, hooked, 

 median projection. Young specimens have all processes of head and body 

 digitiform, ending obtusely, and the dorsal prominences more strongly 

 elevated, giving the back a serrated appearance. Head slightly keeled, 

 rostrum horizontal, forming an equilateral triangie, lateral lobes acute, longer 

 than rosti'um, diverging nearly at a right angle. Side-plate 1 setose, curved 

 forward, 4*^ obliquely truncate below eraargination. Pleon segment 3, 

 postero-lateral angles obtusely quadrate. Eyes small, rounded, dark, wide 

 apart. Antenna 1 not long. 1^* Joint as long as 2*^ and 3'^ combined, 3*^ nearly 

 as long as 2'\ flagellum twice as long as peduncle, with about 25 short, setose 

 joints, accessory flagellum an extremely small nodiile, carrying 2 setules. 

 Antenna 2 much shorter, bent back, ultimate Joint of peduncle shorter than 

 penultimate, flagellum 9-jointed. Gnathopods 1 and 2 in d, 6*^ Joint much 

 widei" than 5*^, bind margin armed with forward curving spines and forming 

 a broadly rounded lobe where it meets the deeply concave palm, finger 

 strongly curved, impinging within the lobe. Gnathopods 1 and 2 in 9 

 comparatively small, 6**1 Joint about as long as 5*^, and scarcely broader, 

 palm in gnathopod 1 somewhat oblique, in gnathopod 2 nearly transverse, 

 finger not streng, matching palm. Peraeopods 3 and 4 rather longer than 

 the rest, 2^ Joint little expanded, slightly tapering distally. Peraeopod 5, 

 2^ Joint nearly straight in front, strongly expanded behind with curved bind 



