348 BULLETIN 100, UNITED STATES NATIONAL MUSEUM 
UNDEUCHAETA PLUMOSA (Lubbock) 
PLATE 35, Figure 540 
Undina plumosa Lupsock, Trans. Ent. Soe. London, new ser., vol. 4, p. 24, pl. 9, 
figs. 3-5, 1856. 
Stations 15; 16; 26; 27; 74; 2195; 8799; 3800; 4009; 4010; 4681; 
4683; 4685; 4687; 4691; 4705; 4730; 4740; 4926; 5120; 5180; 5185; | 
5186; 5227; 5231; 5233; 5234; 5246; 5263; 5819; 5487; 5451; 5595; | 
H. 3789. Present, like the preceding species, in the Monaco, Siboga, 
and Carnegie planktons. The female has no frontal crest, and on the 
dorsal surface of the genital segment is a recurved spine; the fifth legs 
of the male have the form shown in figure 540. 
Genus UNDINULA A. Scott, 1909 
UNDINULA CAROLI (Giesbrecht) 
PLATE 19, FicuRES 252-255 
Calanus caroli GIESBRECHT, Atti Accad. Lincei, Rome, ser. 4, vol. 4, sem. 2, p. 331, 
1888; Fauna und Flora des Golfes von Neapel, monogr. 19, pp. 91, 127, pl. 8, 
fig. 3, 1892. 
Stations 6; 7; 9; 15; 19; 27; 31; 64; 65; 71; 75-78; 470; 3829; 3834; 
3867; 3878; 3901; 3912; 3929; 3930; 3980; 4009; 4010; 4011; 4037; 
4614; 4748; 4926; 5120; 5126; 5129; 5134; 5180; 5185; 5186; 5190; 
5196; 5223-5226; 5228; 52381; 5234; 5240; 5246; 5258; 5262; 5308; 
53819; 5820; 5340; 5386; 5396; 5397; 5399; 5412; 5415; 5422; 5434; 
5487 ; 5507; 5601; 5646; Fiji Islands. This species was well distributed 
in the Stboga and Carnegie planktons and was often abundant, but it 
was not present in the Monaco plankton. There has always been difli- 
culty in separating this from the following species; in fact the two 
are still regarded as the same species by some authors. Scott, how- 
ever, in the Siboga plankton fully established the two males as sep- 
arate species but had to acknowledge that he was unable to separate 
the females. This was reserved for Sars, whose detailed figures of the 
two species reveal the following distinguishing features: 
Female.—Head somewhat narrowed anteriorly, with a smoothly 
rounded forehead, posterior corners of the metasome asymmetrical, 
the one on the left reaching the distal margin of the genital segment, 
closely appressed to the latter, and smoothly rounded at its tip, the 
one on the right not reaching the center of the genital segment and 
inclined outward away from it. The urosome is the same width 
throughout, the anal segment fully as wide as the genital segment. 
The latter is as thick dorsoventrally as it is long and has no dorsal 
posterior spine. The short setae on each caudal ramus are less than 
a sixth as long as the longest one. 
