i 7 2 DISCOVERY REPORTS 



Neomysis; extending for only one-fifth of its length beyond the antennular peduncle. Colosi stated 

 that there was a distinct distal articulation present, but I am unable to find one in any of my specimens. 

 The antennal peduncle is relatively large and extends almost to the distal end of the antennular ped- 

 uncle (Fig. 43 A). There are only one or two thoracic endopods left attached in these specimens. They 

 are very slender and fragile with the carpo-propodus composed of io-ii sub-segments. There is no 

 spine nor acute angle on the outer distal margin of the first segment of the exopods of the thoracic 

 appendages. The exopod of the fourth pleopod of the male is four times as long as the endopod 

 (which is as usually found in the genus), and extends beyond the apex of the telson (Fig. 44 B, C). The 

 uropods are exactly as described by Colosi, except that he stated that there is only one spine on the 

 ventral side of the endopod at the distal end of the statocyst. I find in all my specimens that there are 

 two spines in this position — a large median spine and a smaller one close beside it on the outer side 

 (Fig. 44A). The telson in my specimens is relatively somewhat shorter than as figured by Colosi, but 

 the armature is the same. It is more than half as long again as the sixth abdominal somite (Fig. 44 A). 



Fig. 43. Fig. 44. 



Fig. 43. Neomysis monticellii Colosi. Anterior end of adult male in dorsal view, x 14. 

 Fig. 44. Neomysis monticellii Colosi. A, telson and uropods of adult male, x 14; B, posterior end of 

 adult male in lateral view, x 14; C, distal end of fourth pleopod of male, x 44. 



Colosi gave the length of his specimens as 9 mm. but the largest male in the Discovery collection 

 measures over 10 mm. It is apparently fully mature with the lobe from the antennule very densely 

 covered with setae. 



Distribution. The types of this species were taken in the Strait of Magellan, but there is no record 

 of the depth at which they were living. The Discovery record is from quite close to the coast, north 

 of the eastern end of the Straits in water 49-66 m. in depth. 



Genus Antarctomysis Coutiere, 1906 

 1906 Antarctomysis Coutiere, p. 1. 



Remarks. Coutiere (1906, p. 1) founded this genus for those forms which, while resembling the 

 genus Mysis in the form of the antennal scale and the telson, differed markedly in the form of the male 

 pleopods. I have tried to find some definite generic characters, which apply to both sexes, whereby 

 the genus may be distinguished, but have failed to do so. It is unfortunate that the one constant generic 

 distinguishing character should apply to one sex only, but it is so definite that there can be no doubt 

 as to the validity of the genus. 



The principal characters of the genus are as follows: antennal scale long and narrow in shape, 

 setose all round; apex sharply pointed; distal segment of the 'palp' of the maxilla expanded distally; 

 carpo-propodus of the endopods of the third to the eighth thoracic appendages multi-articulate ; inner 

 margin of the endopod of the uropod armed with a row of spines; pleopods of the female reduced to 



