SYSTEMATIC REPORT 167 



Genus Mysis Latreille, 1803 

 1803 Mysis Latreille, p. 282. 

 1830 Megalophthalmus Leach, p. 176. 

 1882a Onychomysis Czerniavsky, p. 138 (pars); 1887, p. 79. 

 1902 Michtheimysis Norman, p. 477. 



Remarks. The genus Mysis was instituted by Latreille with M. oculata (Fabricius) as the type 

 because the generic name, Cancer, to which it had been referred by Fabricius was preoccupied. 



Only eight species have previously been referred to the genus and none of these is represented in the 

 southern hemisphere. I am now able to record a species belonging to the genus Mysis from waters of 

 the southern hemisphere. Unfortunately the specimens are not adult and there are no males, but 

 they differ sufficiently from all the known species to justify the formation of a new one, Mysis australe. 



Mysis australe sp.n. 



Occurrence: \ b- A 



St. 326. 2. ii. 30 (night). South Georgia, 50-0 m., 2 imm. $?, 14-5 mm. Types. 

 St. 327. 2. ii. 30 (day). West of South Georgia, 50-0 m., 1 imm. $, 14-2 mm. 



Description. General form slender and graceful. Carapace very short anteriorly, anterior margin 

 produced into a small acutely pointed rostrum, which leaves the whole of the eyes exposed in dorsal 

 view (Fig. 41 A). Antenmtlar peduncle slender, first segment equal in length to the second and third 

 together (Fig. 41 A). Antennal scale long and very narrow, apex acutely pointed, eight times as long as 

 broad at its widest part ; no distal suture ; peduncle very small ; only one-fourth of the length of the scale 

 and half as wide ; very strong spine at the outer distal angle of the sympod and another on the ventral 

 surface in the middle of its distal margin. Both these spines are long and acutely pointed (Fig. 41 A). 

 Mandibles with the third segment of the palp rather broader than in other species of the genus (Fig. 

 41 B). Maxilla as shown in Fig. 41 C. First thoracic endopod small with the gnathobasic lobe on the 

 second segment large and well developed, that on the third segment much smaller and only extending 

 half-way along the fourth segment; only a faint indication of a lobe on the fourth segment (Fig. 41 D). 

 Second thoracic appendage moderately long and slender, with the second segment only slightly ex- 

 panded on its inner margin (Fig. 41 E). Third to the eighth thoracic appendages with the carpo-propodus 

 composed of 6-7 sub-segments; nail long and particularly slender (Fig. 41 F). The distal outer angle 

 of the large proximal segment of the exopods of all the thoracic appendages produced into a short acute 

 process. Uropods slender with the endopods slightly shorter than the long telson; armed along the 

 inner margin with a close irregular row of slender spines, which show a definite tendency to an arrange- 

 ment into series of larger spines with smaller ones in the spaces between them. These larger spines 

 increase in size towards the apex of the endopod, and in all three specimens there is a particularly 

 long slender spine right at the apex (Fig. 41 G). Telson very long and narrow, almost three times as 

 long as broad at the base ; width at the level of the base of the cleft about three-fifths of that at the base ; 

 lateral margins almost straight and armed throughout their length with about twenty-eight somewhat 

 irregular spines, which in places show a tendency to an arrangement into series. It may well be that 

 in fully adult specimens this arrangement into series becomes more pronounced. There are five spines 

 on the lateral margins distal to the base of the cleft and there is one larger spine on each apical lobe; 

 cleft deep and narrow with its margins convex distally; armed throughout with a close row of 

 regular teeth; no median setae (Fig. 41 H). 



Length of immature females with very small brood lamellae, 14-2-14-6 mm. 



