12 University of California Puhlicatio)is in Zoology [Vol. 13 



(pi. 2, fig. 34). Tlc\e eyes are large and the corneal part is constricted 

 into two portions. The second and third joints of the antennules are 

 longer and slenderer in females than in males. The seventh legs have 

 well-developed exopods; in the female the endopod is 2-,jointed, ])nt is 

 lacking in males. The copnlatory organs of the males "possess the 

 three processes on the inner lobe, but the spine-shaped process is 

 nearly straight and nearly parallel with the two others . . . ; 

 the lateral process is never hook-shaped and an additional process is 

 wanting" (Hansen, 1911, p. 46). 



Hansen (1911, p. 48) considers six species in the genus and divides 

 them into two groups; among other distinctive characters, he makes 

 use of the presence or absence of bristles on the distal end of the 

 penultimate joint of the second legs. 



Nematoscelis difficilis Hansen 



PI. 1, figs. 1, 3, 4, 12, 15; pi. 2, figs. 22, 34, 35 

 Nematoscelis diJficUis Hansen (1911), p. 48, fig. 18. 



This form is closely allied to N. megalops Sars, according to 

 Hansen, and N. difficilis was established only on the basis of the 

 male copnlatory organs (pi. 2, fig. 22). Our specimens agree, in that 

 respect, with Hansen's description (1911, p. 48, fig. 18). The proximal 

 process is shorter than the terminal but reaches well beyond the middle 

 of the serrated part of the latter. This is the most readily determined 

 difference between N. megalops Sars and N. difficilis Hansen. As 

 mentioned by Hansen (1911, p. 50) the males of difficilis show dif- 

 ferences among themselves in the form of the rostrum. As shown in 

 figures 1 and 3 (pi. 1) the form of the rostrum may be similar in 

 males and females, or it may be very short in the male as shown in 

 figures 12 and 15. I have seen one specimen in which the rostrum is 

 of intermediate length. 



Egg-bearing females average 22 mm. in length, males are not 

 over 20 mm. 



Grcnus Stylocheiron Sars 



Stylocheiron Sars (1885), p. 136. 

 Stylocheiron, Zimmer (1909), p. 22. 

 Stylocheiron, Hansen (1910), p. 113. 

 Stylocheiron, Hansen (1911), p. 52. 



This genus should be readily identified if the third pair of legs 

 is intact. These organs are greatly elongated (see fig. 35, p. 23, in 

 Zimmer, 1909) and the penultimate joint is broadened and in several 



