studies oil marine Oslracods 577 



has foiir joints. According to this writer's work of 1891 a, p. 21, on the other hand, this antenna 

 has five joints; it consists of „einen zweigliedrigen, stielformigeu Schaft und eine dreigliedrige 

 GeiCel". — In G. W. MOllgr's work of 1890 a this antenna is stated (p. 2o8) to have five joints; 

 according to the same investigator's work of 1894, p. 25, on the other hand, it has only four 

 joints, but it was pointed out that sometimes ,,noch ein 3. kleines Glied am Ende des Stammes 

 mehr oder weniger deutlich abgegrenzt ist"; in his work of 1912 G. W. MOlleh gives four as 

 the number of joints in this antenna. 



We find the same differences with regard to this antenna in the genus Huloci/pris. 



All these authors have obviously fluctuated between two alternatives: a four-jointed 

 or a five-jointed first antenna; by the two former authors the latter alternative was adopted; in 

 (}. W. mullein's later works, on the other hand, the former alternative prevailed. 



The question at issue is clearly whether the little collar-like part distally of the second 

 joint ought to be counted as a special joint or if it ought to be taken as a part of the second joint. 

 Which explanation is correct? It seems to me that it is almost a matter of taste. In all the 

 species of the above-mentioned two genera that I investigated this part had no special 

 muscles at all, no muscles are limited to it and none are attached on its proximal boundary. 

 I have nevertheless taken it as a special joint in this work. This is due to the fact that in 

 a number of forms it is exceedingly well marked off; cf., for instance, fig. 8 of Halocyprds brevirostris. 

 I could not find any guidance towards the solution of this problem from the third genus of this 

 family Euconchoecia that I had an opportunity of investigating. 



Is it possible to carry out a quite certain homologization of the joints of the first antenna nomoiogizaiion of 



in the genera belonging to the Conchoecinae-l the joints of the fir.i 



° o o ... antenna. 



In the case of the genera Halocijpris and Conchoecia these joints may with great certainty 

 be homologized. — The highest number of joints on the first antenna in the latter genus 

 is five, and there does not seem to be the least doubt that these joints are homologous 

 to the five joints that characterize in most cases this antenna in Halocypris. This assumption 

 is supported both by the bristles and the nmsculature of this limb. 



The number of bristles is, as we know, quite the same in these two genera: the first and 

 third joints have no bristles at all, the second joint has a single bristle dorsally and the fourth* 

 and fifth bristles have two and three bristles respectively. In addition these bristles are of 

 about the same type in the genus Halocypris as in the females of Conchoecia. 



All the species of Conchoecia investigated and described by me below have a practically 

 identical muscular system in this antenna. It is true that slight exceptions from the type 

 described below can be observed, but these are of no importance for this question, so that they 

 are not mentioned here. In the males of this genus we find the following muscles in this antenna 

 (type: C. symmetrica G. W. MOLLER; cf. fig. 7 of this species): The first joint contains two 

 muscles. One of these, the extensor of the second joint, is very strong, simple, and has the nature 

 of almost a pure extensor; proximally it is attached dorso-proximally on the first joint, distally 

 on the second joint dorso-proximally, somewhat laterally. The other of these two muscles is 

 also strong, in most cases divided into two (oidy exceptionally into more) well defined parts, 



* With regard to a larger number or bristles in Conchoecia serrulata see the remark on lliis species below. 

 Zoolog. bidrag, Upps-ila. Suppl.-Bd. I. 73 



