55 



oblong, rounded, free lobe directed backwards and outwards; the wing covers the major part 

 of the upper surface of the marsupium outside the abdomen. The plate-shaped four posterior 

 pairs of female pleopods not quite twice as broad as long. Pseudobranchial lamellae of the male 

 pleopods very large, bilobed (PI. Vll, fig. 3/; PI. VIII, fig. i a), the outer lobe three or four 

 times as large as the inner, and both without sharp angles. Exopod of third male pleopod 

 (PI. Vni, fig. la) about half as long again as the endopod ; its terminal part exceedingly 

 complicate with several spines (figs, i d and i f), some of which developed in a most aberrant 

 way: the terminal spine or process is bifurcate near the base with one of the rami short, while 

 the other is extremely long, somewhat curved and its most distal part bent in the opposite 

 direction ; an extremely thick, distally hook-shaped body, probably a transformed spine, is seen 

 along the outer and lower side of the last two (or three) joints. (Fig. i d represents this terminal 

 part of an adult male from behind, fig. i c the same from in front, while fig. i d shows the 

 structure of the part of an immature male from behind). 



Uropods with the endopod moderately slender, distinctly overreaching the telson and 

 somewhat longer than the exopod, the end of which is broadly rounded, nearly truncated (fig. T,n), 

 while the outer margin bears a number of moderately short, near the end longer, spines along 

 about three-fourths of the length. Telson (PI. VII, fig. 3;;/) slightly more than three times as 

 long as broad, with its proximal part a little widened: from this part the lateral margins 

 converge very feebly to the end and are furnished with a good number of spines, several of 

 which are conspicuously longer than the others; the terminal incision nearly as in A. typica. 



Length of a large adult male 9.2 mm., of an ovigerous female 7 mm. 



Remarks. — This species is somewhat larger than the three other species hitherto 

 known, and it is readily distinguished by the shape of the frontal plate and rostral process, by 

 having the end of the exopod of the uropods very broadly rounded and nearly transverse, by 

 the large, subtriangular wings of the first abdominal segment in the female, finally by the large 

 process on the gnathopods and the complicate structure of the terminal part of the exopod of 

 third pair of uropods in the male. 



Distribution. — The Copenhagen Museum possesses this species from the Bay of 

 Bengal, i specimen ("Galathea" Expedition); from lat. 9°4o'N., long. 108° E., i specimen 

 (Capt. Andrea), and from two localities in the Gulf of Siam, viz. between Koh Mesan and 

 Cape Liant, 5 — 8 fathoms, i specimen, and the northern side of Koh Mesan, 10 — 15 fathoms, 

 I specimen (Dr. Th. Mortensen). 



Gastrosaccus Norman. 

 {Pontoniysis Czern.; Haplostylits Kossmann; Chlamydopleon Ortmann, not Illig). 



Of this genus G. O. Sars (in his Mediterranean Mysidae) has given an excellent and very 

 detailed description, to which the readers are referred. Here I will add only a few supplementary 

 or restricting remarks to that diagnosis, and most of these remarks are due to structural features 

 observed in the species to be described presently. 



The free lobes at the hind margin of the carapace are wanting in some forms. Maxillipeds 



