158 BULLETIN 100, UNITED STATES NATIONAL MUSEUM 
Stations 3799 ; 3901 ; 4588 ; 5208; 5209 ; 5240; 5262; 5840; 5348; 5415; 
5424; 54387; 5646; 5651; Sabtan Island, Philippine Islands. This 
species was well distributed in the Siboga (50 stations) and Carnegze 
(37 stations) planktons but did not appear in the others. 
ACROCALANUS MONACHUS Giesbrecht 
PLATE 2, FIGURE 6 
Acrocaianus monachus GIESBRECHT, Atti. Accad. Lincei, Rome, ser. 4, vol. 4, sem. 
2, p. 333, 1888; Fauna und Flora des Golfes von Neapel, monogr. 19, pp. 171, 
175, pl. 6, figs. 26, 81; pl. 10, fig. 38, 1892. 
Stations 16; 3683; 3765; 3829; 3901; 8912; 4722; 5155; 5223; 5226; 
5246; 5262; 53820; 5386; 5399; 5487; 5488; Fiji Islands. Found at 
4 stations in the Siboga plankton and 387 in the Carnegie plankton but 
not present in the others. 
Genus AEGISTHUS Giesbrecht, 1891 
AEGISTHUS MUCRONATUS Giesbrecht 
Aegisthus mucronatus GIESBRECHT, Atti Accad. Lincei, Rome, ser. 4, vol. 7, sem. 1, 
p. 476, 1891; Fauna und Flora des Golfes von Neapel, monogr. 19, pp. 573, 
577, pl. 46, figs. 46-49, 51; pl. 49, figs. 2, 3, 6, 10, 1892. 
Stations 3; 3799; 4700; 4734; 5120; 5185; 5262; 5320. This species 
was taken in the Siboga plankton in 18 vertical hauls from 700 to 
1,500 meters to the surface. Six of the Albatross hauls were vertical 
ones from 500, 350, 300, and 100 fathoms to the surface; two were sur- 
face tows. It appears otherwise only in the Monaco plankton list and 
must be regarded therefore as a poorly distributed species. M. W. 
Johnson (1937, p. 506) states, “On the west coast of America it is 
probable that there is a continuous deep-water distribution [of 
mucronatus| extending at least from southern California to the 
Straits of Juande Fuca * * *.” All the specimens of this species 
from stations 3799 and 5262 were males and were identified by Sars 
as Aegisthus dubius. A. dubius was originally established by Sars 
cn males in the Monaco plankton. Farran (1926, p. 3801) in his dis- 
cussion of the Research plankton suggested that these were the males 
of the species mucronatus. More recently M. W. Johnson (1937, p. 
505) has positively identified copepodid and adult dubéus males as be- 
longing to the species mucronatus. These Albatross specimens there- 
fore must be regarded as A. mucronatus. 
AEGISTHUS SPINULOSUS Farran 
Aegisthus spinulosus Farran, Ann. Rep. Fisheries, Ireland, 1902-03, pt. 2, app. 
2, p. 46, pl. 12, figs. 8-14; pl. 13, figs. 14, 1905. 
Stations 5120; 5185; 5226; 5297; 5262; 5437. Originally estab- 
lished by Farran upon a single female specimen and does not appear 
