^)l^2 TACK sivOnsifKun 



widtli at about tlif iniiltlli' and tlu- antcrinr part iif tlio slicll loiisicU'ralily lar^^cr tliau tlii' postfrii)!' 

 part; tlu« sido i-tmtours aro ratluT dciiilodly concave just hohiiul the middle, apart from which 

 thev are evenlv curvetl; the anterior and posterior ends are broadly j)ointed, the rostrum is 

 almost symmetrical. The shoulder vault is rather well dcxcldiied and always well rounded. 

 The surface of the shell is bare and has a sculpture of the type reproduced by 

 G. \V. MCl.l.KK. Seen from inside: Selvage: This is in most eases smooth on the rostrum 

 and along the anterior margin of the shell and the anterior half of the ventral margin of the shell; 

 posteriorly it is exceedingly finely serrulated. It has no spinedike process on the rostrum. 

 The glands are as described by G. W. MtlLLEK; the left unsymmetrical gland has its exit just 

 at the posterior dorsal corner of the shell. There is an almost complete absence of medial glands 

 along the posterior margin of the shell (apart, of course, from the dorsal medial glands that are 

 well developed); the few that are found emerge with single pores a short distance inside the 

 margin of the shell. At the posterior dorsal corner there is a well developed hinge-socket and 

 hinge-tooth; see the accompanying fig. 4 (c? — ?). 



First antenna: — The first joint is somewhat shorter than the second. The 

 boundary between the original second and third joints is scarcely or not at all developed. The 

 b-, d- and e-bristles are in most cases subequal, about one and a half times the length of this hmb 

 or somewhat shorter. The e-bristle is armed with from eight to thirteen spines, according to 

 G. W. ilCLLEK; in C. Claus's figures (1891 a) there are from seven to fourteen; on the specimens 

 investigated by me I counted from eleven to thirteen; these spines agree with the type reproduced 

 by C. Glaus, 1891 a. Proximally of the spines there are sparse and very short secondary bristles 

 on the anterior side of this bristle. These three bristles are bent at an angle, which is in 

 most cases a rather decided one, at about two-thirds of the way along them; they are not 

 widened distally and have no pad-Hke formations. G. W. Mt'LLEU states that the b- and 

 d-bristles are bare; in the specimens investigated by me I was able in most cases to find 

 a few short, fine, distally pointing hairs about opposite the spines of the e-bristle. The a- 

 and c-bristles are of about the types shown in pi. XX, fig. 17, C. Claus, 1891 a. All the joints 

 are quite bare. 



Second antenna: — Protopodite: In specimens with shells 0,8 mm. 

 long this measured about 0,4 mm. Exopodite: The proportion between the length of this 

 branch and that of the protopodite is about 10 : 16. The proportion between the length of the 

 first joint and the total length of the eight distal joints is about 10 : 4. The longest natatory 

 bristles are about a quarter longer than this branch. The first joint is bare. Endopodite: 

 First joint: The processus mammiUaris has no distal verruca and is comparatively small. The 

 a- and b-bristles have short hairs. Second joint: The c-, d- and e-bristles are of about the same 

 relative lengths as in the figures 13 and 14 of C. symmetrica. The g-bristle is, as a rule, somewhat 

 longer than the protopodite, somew^hat sword-shaped distally and furnished with exceedingly 

 short and fine hairs. The f-bristle is somewhat shorter than the protopodite, narrow, bare and 

 furnished with very short and fine hairs. Third joint: The clasping organs are of about the types 

 reproduced by G. W. Ml'LLER, 1906 a, pi. XXX, figs. 4 — 1; they have rather decided transverse 

 creases distally. The h-, i- and j-bristles are subequal, about half the length of the g-bristle 



