Sludii's on iiiaiinr Oslracods 461 



joint. One can understand indirectly from the text that these authors considered that the 

 conditions were the same in the other male investigated by them, the male of A. teres. — Finally 

 I wish to mention in passing that J. A. Cushman, 1906, p. 366 states that the ,,last joint of 

 antennula in male 3-jointed". As this statement does not even agree with the figures given 

 by this author, pi. 29, figs. 21 and 22, it may be disregarded here. It ought perhaps also to be 

 mentioned that the figures in question are not correct either. 



As is shown by the description of the genus given above the facts ascertained by me 

 do not agree with any of the preceding authors' accounts. All the males of this genus* that 

 were investigated by me had a seven-jointed first antenna, the original third and fourth 

 joints were always differentiated; the boundary between the fifth and sixth joints was sometimes, 

 however, at least partly, not distinctly developed. The part on which the (d-), e-, f- and 

 g-bristles are fixed ought perhaps to be distinguished as a special eighth joint (see p. 449 above). 



A more detailed study of the structure of the first antenna seems to show with all desirable 

 clearness the incorrectness of G. O. Sars's view that the fifth (i. e. the original sixth) joint of 

 the female first antenna should in the male be divided into two joints and that the small part 

 of the male first antenna on which the b-, c-, f- and g-bristles are situated corresponds to the 

 whole of the little end joint of the female first antenna. 



The small end joint of the female first antenna is moved by three muscles, namely one 

 extensor and two flexors. The extensor is attached proximally at the anterior part of the 

 boundary between the fourth and fifth joints, distally on the end joint anteriorly and somewhat 

 laterally. Of the two flexors one arises posteriorly at the boundary between the third and 

 fourth joints, and is attached distally on the end joint posteriorly and somewhat laterally; 

 the other arises posteriorly at the medial boundary between the fourth and fifth joints, and is 

 attached distally on the end joint somewhat medially. In addition there is a very weak, almost 

 completely reduced flexor, arising posteriorly at the lateral boundary between the fourth and 

 fifth joints, and fixed distally on the end joint posteriorly and somewhat laterally, in most 

 cases a little in front of the flexor that arises posteriorly at the boundary between the thiixl and 

 fourth joints; cf. fig. 10 of A. Grimaldi. The seventh joint of the female first antenna is moved 

 by quite the same muscles in all the species belonging to the sub-family Cypridininae that have 

 been examined by me. These muscles are also found on the male first anteima in the family 

 Asteropidae. The only differences are that the proximal fastenings of the two flexors that arise 

 on the boundary between the fourth and fifth joints are displaced somewhat anteriorly and that 

 the lateral of these two muscles is much more strongly developed. These four muscles do not, 

 however, move the small part that G. 0. Sars has homologized with the female end joint, but 

 the large joint that I have described above as homologous with the female seventh joint; cf. 

 fig. 11 of ^. Grimaldi. Another reason against the assumption put forward by G. O. SarS that 

 the original female sixth joint has been split into two joints in the male may possibly be con- 

 sidered superfluous, but I shall, however, state it here. There is always a bristle distally-medially 

 on this joint in the female first antenna (in this genus as in the family Cypridinidae). The same 



* liesidcs tlic niak'S of A. GriiiiaUli, wrvcgica arul curtti I iiivt'sligali'd anothci' inali' of this iffiuis wlii. h is not 

 iiicludud in this publication; the result was Ihu same as for tiio Uiree spucies nioalioned. 



