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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 .1. A. CuSHMAN, 1906, p. 366 states that the „last joint of
antennula in male 3-jointedu. As this statement does not even agréé 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 fiexors. 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 fiexors 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 media! 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 third 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 antenna in the family
Asteropidae. The only differences are that the proximal fastenings of the two fiexors 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. O. 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 A. 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
considered 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
* Resides the males of A. Grimaldi, norvegica and curta 1 in vesligaled nnotlier male of this gemis whieh is not
included in this publication; the result was the same as for the three species mentioned.
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