NYCTIPHANES SIMPLEX. 229 



Remarks. — Tliis species is allied to N. ausiralis G. 0. S., but differs in several 

 features. In order to point out and illustrate these differences I have given on 

 Plate 6 figures of the antennular peduncles of both sexes and of the copulatory 

 organs of N. australis; the figures were drawn from two cotypes of Sars. 



The leaflet from first joint is much smaller than in N. simplex and consider- 

 ably broader than long (figs. 3a-3d), subtriangular, with the outer margin convex 

 and very oblique, and it terminates in a more or less acute tip bent upwards and, 

 in one of the specimens drawn, somewhat forwards and placed almost above the 

 inner margin of the joint, furthermore no transverse, vaulted part is seen at the 

 outer side below the base of the leaflet. The antennular peduncles in the male 

 are still somewhat tliicker, those of the female still more slender than in N. simplex. 

 In the male (fig. 3a and 3b) a high, compressed, keel-shaped protuberance is seen 

 near the end of second peduncular joint, and the third joint is .somewhat thicker 

 than in A'', simplex, with about six minute hairs, but no stiff setae, on the inner 

 side. The copulatory organs (fig. 3e) have the most distal part of the inner 

 lobe considerably broader than in N. simplex, the proximal half of the outer 

 margin of this lobe differs in the shape of the protuberances from that species, 

 but the most important difference is shown by the median lobe (Im.), which in 

 A'', australis has the lateral process placed as in N. simplex, but the lobe itself 

 projects along that process to its end; if this lobe had been cut off opposite 

 the insertion of the process we would have the structure found in N. simplex. 

 The female examined of N. ausiralis is 13.5 mm., the male 15 mm. 



Distribution. — In 1894 Ortmann (Bull. Mus. Comp. Zool., 25, p. 100) enum- 

 erated nine localities ior Nyctiphanes australis: — Gulf of Panama, Galapagos, 

 Gulf of California, and some Stations in the Northern Pacific between San Fran- 

 cisco, and the Hawaiian Islands. From the U. S. National Museum I have 

 received specimens from these Stations and an examination gave the result, 

 that the two specimens from "Survey" Sta. 54 and "Sui'vey" Sta. 74, both 

 Stations in the North Pacific between San Francisco and the Hawaiian Islands, 

 are males of Euphausia recurva H. J. H., while the specimens from the seven 

 other Stations belong to N. simplex and not to N. australis. The latter species 

 is hitherto only known from the sea around the Southeastern part of Australia; 

 in 1911 I established A^. capensis on the specimens mentioned by Stebbing in 

 1905 and 1910 as taken off Cape St. Blaize, South coast of Africa, and by him 

 referred to A'', australis. 



