40 



I longer spine on each of the two preceding joints and i spine on the side of second joint ; 

 third joint of the shaft is produced in a protuberance below the insertion of the main "branch" 

 and on that protuberance two spines are inserted, both strongly curved, the lower robust, 

 extremely long, reaching the spines on fifth joint of the main "branch", the upper spine scarcely 

 half as long as, and much more slender than, the 'other. Antennal squama reaches to the end 

 of second joint of the antennulae. The coxae of third legs (fig. 5^^) with a tooth at the distal 

 inner angle, while the trochanter has no tooth near its inner end. Genital coxae (fig. 5 d) con- 

 siderably broader than long, anteriorly very broadly rounded. Exopod of uropods (fig. 5^) nearly 

 four and a half times as long as broad; the ciliated part of the outer margin is almost as long 

 as the glabrous part. 



The petasma is most characteristic (figs. $e — ^f). Pars astringens is completely wanting; 

 pars externa {e.) is somewhat large, about three times as long as broad, with the inner margin 

 rather concave, so that the plate is broader towards the base and considerably beyond the 

 middle than at the middle. Pars media has its proximal part somewhat broader than in the two 

 preceding species, and its basal margin is .somewhat feebly concave, while the outer corner is 

 more produced than the inner. Processus ventralis {pv.) which originates before the middle of 

 pars media, has the proximal half thick, ovate, while its distal half is a slender, acute needle. 

 When considering the portion beyond the insertion of processus ventralis as the capitulum (r.), 

 its proximal major part is moderately thick, while the most distal part is broader, somewhat 

 widened especially inwards and forwards, oblique-ovate, with numerous hooks on the outer part 

 both on the posterior and the anterior surface. 



Length 12.5 mm. 



Female. — Eyes and antennulae nearly as in the female A. Si6ogcc\ lower flagellum 

 scarcely as long as third and half of second peduncular joint combined ; antennal squama does 

 not quite reach the middle of third antennular joint. Coxae of third pair of legs (fig. i a) in the 

 main as in the females of A. vulgaris and A. SiSogo"; trochanter without any tooth near the 

 distal inner end. Exopod of uropods as in the male, consequently differing from the females 

 of the two species mentioned in having the ciliated part of the outer margin almost or fully 

 as long as the glabrous part. 



The genital area (fig. i a) is characterized by a large, subquadrangular plate somewhat 

 broader than long; the plate begins between the posterior part of the coxae of third legs 

 and reaches considerably behind the transverse furrow separating the last thoracic segment 

 from the penultimate; when the animal is inspected from the side, it is easily observed that 

 this plate protrudes freely below the ventral surface of the segments, and that a longitudinal 

 section through the plate would be very oblong-triangular; seen from below the plate, has its 

 posterior angles broadly rounded and the posterior margin otherwise rather deeply concave ; 

 each lateral part of the plate is elevated as a kind of keel, and the median line and the 

 posterior margin are a little elevated, so that the plate has two hollowed areas. 



Length of the largest specimen 15 mm. 



Varietas vcl sp. n. ? — The Copenhagen Museum possesses 5 females taken pelagically 

 at lat. 24°i7'N., long. ii8°i5'E. by Capt. Suenson. They agree with A. dispar in all features 



