141 

 11. Argissa typica, Boeck. 



(PL 48). 



Argissa typica, Boeck, Crust amphip. bor. & arctica, p. 45. 

 Syn: Chimeeropsis danica, Meiuert (male). 



Body as a rule strongly curved, exhibiting at first sight an immistak 

 able resemblance to that of an Ampelisca. Cephalon exceeding in length 

 the first 2 segments of mesosome combined, subtruncated in front, lateral 

 corners but little projecting and narrowly rounded. First pair of coxa 1 plates 

 rather large, gradually widening distally, with the edges evenly curved and 

 provided with slender bristles; the 2 succeeding pairs narrowly triangular in 

 form and rapidly decreasing in size; 3rd pair very small; 4th pair in female 

 of extraordinary size, oval in form, and very slightly emarginated posteriorly 

 in its upper part, the edges evenly curved and smooth, those in male cons! 

 derably smaller; the 2 succeeding pairs of moderate size, with the posterior 

 lobe much deeper than the anterior. Last pair of epimeral plates of meta- 

 some nearly rectangular. Urosome in female quite smooth above, in male 

 with 2 vaulted transverse expansions, the posterior very large and overhanging 

 the last segment. Eyes rounded in form, each containing 4 small bigeminous 

 lenticular bodies arranged in regular distance from each other, pigment red 

 with a whitish coating. Superior antennae in female about the length of the 

 cephalon and the first 3 segments of mesosome combined, joints of the peduncle 

 regularly diminishing in size, the 1st being about as long as the other 2 

 taken together, all provided with simple scattered bristles, tlagellum very 

 slender, about the length of the peduncle, and composed of 7 articulations; 

 accessory appendage very small, scarcely as long as the last joint of the 

 peduncle, biarticulate, terminal joint extremely minute. Same antennas in 

 male a little more slender, tlagellum nearly twice the length of the peduncle, 

 its first 2 articulations fused together into a single rather large joint, provided 

 posteriorly with numerous transverse rows of fine sensitive cilia. Inferior 

 antennas in female nearly twice as long as the superior, joints of the peduncle 

 narrow cylindric, and nearly smooth, the penultimate one by far the longest ; 

 flagellum scarcely longer than the two outer joints of the peduncle combined, 

 and composed of 7 articulations; those of male much more slender and don- 

 gated than in female, though not quite attaining the length of the body, tla- 

 gellum about the length of the peduncle and composed of the same number 

 of joints as in the female. Grnathopoda densely setous, propodos mneli shorter 

 and narrower than the carpus, dactylus slender and feeble. The 2 anterior 

 pairs of pereiopoda scarcely attaining the length of the gnathopoda and in 

 female almost entirely concealed by the large 4th pair of coxal plates. Penul- 

 timate pair of pereiopoda a little more slender than the antepenultimate ones. 



18 b Crustacea. 



