SYSTEMATIC REPORT 93 



equal in length. The form of the eyeplate is, however, quite typical of P. armatum and the form and 

 armature of the telson so closely resemble the descriptions of that species, that, in spite of the dif- 

 ferences in the scale, I have no hesitation in referring them to armatum. 



Distribution. Type specimens from 54 u'-54° 24' S., 36 18-36 22' W., South Georgia 

 (Hansen, 1913, p. 12) and three records from Cumberland Bay, South Georgia (Rustad, 1930, p. 7). 



If the specimens from the South Orkneys are accepted as belonging to this species, the slight dif- 

 ferences between them and the specimens from South Georgia could be attributed to the distance of 

 their place of capture from the area in which all the other records were made. 



P. armatum has previously been recorded in temperatures ranging from —0-25° C. to 1-45° C. The 

 Discovery material extends these limits — the lowest temperature being —0-8° at station 162 and the 

 highest 2-08° C. at station 42. 



Pseudomma sarsi (W.-Suhm in MS.) G. O. Sars, 1884 



1884 Pseudomma sarsi G. O. Sars, p. 37. 



1885 a Pseudomma sarsi, G. O. Sars, p. 189, figs. 

 191 3 Pseudomma sarsi, Hansen, p. 13. 



1930 Pseudomma sarsi, Rustad, p. 7, figs. 



. Occurrence: 



St. 45. 6. iv. 26 (night). East of Jason Light, South Georgia, 270-238 m., 1 juv. J (broken). 



St. 140. 23. xii. 26 (day). South Georgia, 136-122 m., fragments. 



St. 142. 30. xii. 26 (day). East Cumberland Bay, South Georgia, 273-88 m., 1 adult $, 9-8 mm., 2 juv. ??. 



St. 149. 10. i. 27 (day). Cumberland Bay, South Georgia, 200-234 m., 1 adult $, 11 mm. 



St. 154. 18. i. 27 (day). South Georgia, 160-60 m., 3 adult $$, 10-11 mm. 



St. 162. 17. ii. 27 (day). South Orkneys, 320 m., 1 imm. <J, io-8 mm. 



St. 167. 20. ii. 27 (day). South Orkneys, 344-244 m., 1 adult $ with empty brood pouch, 13-5 mm. 



St. 1957. 3. ii. 37 (day). South Shetlands, 785-810 m., 1 juv. (J, 1 ?, 11 mm. 



St. WS 213. 30. v. 28 (day). North of Falkland Is., 239-249 m., 1 $, 9 mm. 



St. WS 234. 5. vii. 28 (night). North of Falkland Is., 207-195 m., 1 & 9-5 mm., 1 juv. $. 



St. WS 818. 17. i. 32 (day). Patagonian Shelf, 272-278 m., 1 adult <J (damaged). 



Remarks. In many respects this species closely resembles both P. roseum G. O. Sars and P. trunca- 

 tum S. I. Smith, but may be distinguished by the form of the antennal scale and by the armature 

 of the apex of the telson. Although there appears to be some variation in the relative length of the 

 apex of the antennal scale in P. sarsi, it never measures more than one-fifth of the total length of the 

 scale, and may be less, while in P. roseum it occupies from one-third to one-half of the total length and 

 in P. truncatum one-third to one-fourth of the total length. 



I find that in these specimens the apex of the telson is more rounded than in Sars's figures, but it is 

 almost precisely as figured by Rustad (1930, p. 8) and in this respect the species may readily be dis- 

 tinguished from P. truncatum. It can be distinguished further by the arrangement of the apical 

 spines. These are set closely together and increase regularly in size towards the middle line. There are 

 usually four pairs of these spines; the most distal lateral spine is set close to the apex and is inter- 

 mediate in length between the large apical spines and the small lateral ones. In both P. roseum and 

 P. truncatum, there are usually two pairs of apical spines and they are more spaced than in P. sarsi. 



The specimens which I have here referred to P. sarsi have been difficult to identify. Although they 

 agree in general form, they show variation in the serrulation of the eyeplate, in the length of the apex 

 of the antennal scale, in the relative lengths of the rami of the uropods and in the number of small 

 spines arming the lateral margins of the telson. The material is not sufficiently well preserved nor are 

 there enough specimens to decide whether these variations are of specific value. 



