iz6 DISCOVERY REPORTS 



Remarks. This species was instituted by Zimmer for two specimens taken in a vertical haul 

 (3000-0) m. off the west of the Cape of Good Hope. The types consisted of an adult <3 of 9 mm. and 

 an immature female. Specimens of the same size in the Discovery material agree so closely with 

 Zimmer's description and figures, that I have no hesitation in referring them to his species. The only 

 difference I can find is in the largest specimens of the Discovery material, where the anterior margin 

 of the carapace extends farther forward than in Zimmer's figure and partially covers the bases of the 

 eyestalks. In Fig. 30 I have copied some of Zimmer's figures and placed them beside corresponding 

 figures of an adult female from station 254. A comparison shows not only how closely they resemble 

 one another, but also the slight difference which I have mentioned. In his description Zimmer 

 noted a single blunt spine on the inner margin of 

 the endopod of the uropod at the distal end of the 

 statocyst, but did not figure it. I have found this spine 

 to be present in all my specimens, but it is by no means 

 easy to see unless the appendage is dissected, for it is 

 blunt and lies on the ventral side of the endopod a little 

 way in from the margin, barely projecting at all 

 (Fig. 30 B). The finger-like process on the inner margin 

 of the eye is very small in younger animals, but in adults 

 of both sexes it lengthens and curves outward in front 

 of the cornea (Fig. 30 A). 



Nouvel (1943, p. 75) doubtfully referred a damaged 

 female specimen captured off the Azores in a vertical 

 haul, 2500-0 m., to this species. He pointed out that 

 the rostral plate formed a more obtuse angle than in 

 Zimmer's types and that the rostrum was less marked. 

 He also noted that the scale was somewhat narrower 

 than in L. capensis and that the spine on the outer 

 margin was more acute. 



In his review of the Mysidacea of the United States 

 National Museum, written just before his death in 1943, 

 my husband (Tattersall, 1951, p. 120) referred a number 

 of specimens captured off the Bermudas to L. capensis. 

 He had not seen Nouvel's 1943 publication and stated 

 that the species had only once been recorded. He pointed 

 out that his specimens agreed very closely with the types, 

 but that the rostral plate had straight sides set at about an angle of 120 , with the apex bluntly 

 rounded and not produced. I made figures of the telson and one uropod and of the antenna, but 

 not of the anterior end. 



In reviewing the whole of the records, I am of the opinion that we have here two distinct species, 

 one the original L. capensis from the South Atlantic and the other from the Azores and Bermudas. 

 I suggest for the second species the name L. nouveli after Professor Nouvel who first published its 

 description. 



This new species differs from L. capensis as follows : 



(1) Rostrum. The anterior margins of the rostral plate are straight, converging to an 

 obtuse angle and not produced forward between the eyes as a bluntly rounded rostrum as in 

 L. capensis. 



Fig. 30. Longithorax capensis Zimmer (A-C for com- 

 parison with Zimmer's figures D-F). A, anterior 

 end of female in dorsal view; B, telson and right 

 uropod of female in dorsal view; C, distal end of telson 

 (enlarged); D, anterior end of male (after Zimmer); 



E, telson and right uropod of male (after Zimmer); 



F, left antennal scale (after Zimmer). 



