studies on marine Ostracods 627 



an almost symmetrical rostrum, posteriorly it is somewhat pointed. The shoulder vault is 

 well developed, but is always rounded. To judge Irom the literature the surface 

 sculpture varies: G. 0. Sars writes, 1865, p. 117: ,,striis numerosis densissimis et decussatis 

 reticnlatae" ; G. W. MULler, 1901: „Bisweilen zeigt die Schale eine deutliche Streifung. Meist 

 erkennt man als Rest einer Streifung nur eine Zahnelung resp. Felderung an der vorderen Halfte 

 des Ventralrandes, und audi diese kann fehlen". Cf. also V. VA\RA, 1906, p. 42. The specimens 

 investigated by me showed an agreement with G. 0. Sars's original description with regard 

 to this character, but the reticulation was sometimes rather diiticult to verify. The variation 

 is perhaps only apparent; cf. G. W. MtlLLER, 1906a, p. 33. The surface of the shell 

 is without or practically without hairs. Seen from inside: Selvage: This is in most 

 cases smooth>edged on the rostrum and has no spine-like process. It is qiute smooth-edged or 

 sometimes exceedingly finely serrulated along the anterior margin of the shell and the 

 anterior half of the ventral margin of the shell; it is finely serrulated along the posterior half of 

 the ventral margin of the shell and along the ventral half of the posterior margin of the shell. 

 There are compound glands as described by G. W. MUller, 1906 a. The glands along the 

 posterior margin of the shell are moderately large and have their exits on the margin of the shell 

 itself; only one or a few emerge (with a simple exit) between the list and the margin of the shell. 

 There is no hinge-socket or hinge-tooth at the postero-dorsal corner of the shell. 



First antenna: — The first joint is comparatively long and has in most cases 

 a rather distinct contraction near the base; cf. the accompanying fig. 14; the proportion between 

 the lengths of the first and second joints is about 8 : 5. The b-, d- and e-bristles are in most 

 cases subequal and somewhat shorter than this limb. E-bristle: This bristle has at about two- 

 thirds of the way along it an oval plate like a suctorial organ of about the type reproduced 

 in fig. 15; the edge of this plate is — ■ at least as far as I could observe — smooth. Just distally 

 of this plate there is a somewhat varying number of short and rather powerful spines, arranged 

 in two groups situated near each other; the number of spines is most frequently about the same 

 as in the accompanying fig. 15. Just distally of these spines this bristle is in most cases bent 

 at a distinct angle. The part of the bristle distally of these spines is closely and finely annulated 

 or partly hyaline, bare, and is not at all or only slightly widened. (Note that the proportion 

 between the sucker-like plate and the part of this bristle situated distally of this is quite incorrect 

 in G. W. MUller's work of 1901.) The part of this bristle situated proximally of the sucker-like 

 plate is furnished on its anterior side with sparse and exceedingly short bristles (scarcely percept- 

 ible with Reichert's ocul. 4, Leitz's immersion V,,). B- and d-bristles: These seem sometimes 

 to be qaite bare, sometimes one or both of them has a rather small number of short, moderately 

 strong or rather weak spines about opposite the sucker-like appendage of the e-bristle. The 

 distal part of these bristles is of about the same type as that of the e-bristle; the bending into 

 an anele is about the same as in the latter bristle or in most cases somewhat weaker. None of 

 these three bristles has distinct pad-like formations; it is to be noted, however, that their distal 

 parts have in certain positions a structure that reminds one rather strongly of such formations. 

 The a-bristle is very long, in most cases about as long as or somewhat shorter than, sometimes 

 even somewhat longer than the b-, d- and e-bristles; in most cases it is more or less straight. 



