Studii's on iiiiii-iiio Oslracods 569 



The upper iucisur lip never grows over the lower one. The sculpture of the surface is 

 in most cases weak. The selvage is always laruelliform, in most cases well developed* both on the 

 rostrum and along the anterior and ventral margins of the shell. It runs somewhat within and 

 practically parallel with the ventral and posterior margins of the shell, being only slightly more 

 distant from the margin posteriorly than it is anteriorly. It approaches more and more closely 

 to the margin of the shell just beneath the rostral incisur and in the incisur it runs on the margin 

 of the shell itself. On the rostrum the selvage runs on the „Biichtlinie", i. e. on the original 

 margin of the shell. The list runs from a point somewhat behind the rostral incisur in a uniform 

 arcuation along and practically parallel to the ventral margin of the shell, somewhat inside the 

 selvage ; it has a whole margin and is in most cases very narrow, sometimes even difficult to establish 

 with certainty. The inner line is in most cases very difficult to follow with certainty; it runs 

 about parallel to the free margin of the shell somewhat inside the list. Close to the margin of 

 the shell there always emerge very numerous glandular cells, which, as G. W. MULler pointed 

 out, 1906 a, may be conveniently divided into medial and lateral glands according to whether 

 they emerge medially or laterally of the margin of the shell. A number of these glandular 

 cells are concentrated in more or less large groups, which emerge with common pores or on 

 a glandular field. Each shell has at least two such groups, one on each valve, each group with a 

 single opening. As these two compound glands almost always have different positions on the two 

 valves they were described by G. \V. MCller, 1906 a, as ,,die unsymmetrischen Driisen". In 

 a number of forms (genus Conchoecia) there are, in addition to ,,die unsymmetrischen Driisen", 

 two other compound glands developed; these are ,,die lateralen Eckdriisen" and ,,die dorsalen 

 medialen Driisen", the former emerging with a single pore, the latter on a glandular field. 

 „Die lateralen Eckdriisen" emerge on the right valve laterally of or close to and dorsally of the 

 (right) ,,unsymmetrische Driise" and on the left valve about opposite to this place. ,,Die 

 dorsalen medialen Eckdriisen" are two in number, one on each valve, and emerge symmetric- 

 ally just ventrally of the postero-dorsal corner of the shell. There are very few glands on the 

 surface of the shell. The joined part of the lamellae is in most cases narrow along the whole 

 of tlie free margin of the shell. At or just in fi-ont of the postero-dorsal corner of the shell; 

 just behind the joined edges of the hinge, there is often on the left valve a more or less 

 powerful, oblong, hinge-tooth, and on the right valve a corresponding hinge-socket. 



First antenna: — This has no or has more or less marked dimorphism. — It 

 is moderately long or relatively short and varies in strength; the number of joints varies, but 

 there are never more than five. Its (original) first joint is always without bristles. It is always 

 furnished distally with a number of sensory bristles which are developed as thin-walled, hyaline, 

 bare filaments, in most cases somewhat rounded distally. This limb is chiefly a sensory organ; 

 it seems never to be used as a locomotory organ; in the case of the males it is often used for 

 seizing the female. 



Second antenna: — This always shows strong dimorphism; it is, as a rule, 

 developed somewhat more powerfully in the male than in the female. — Exopodite: This 

 is about the same in both sexes. The first joint has disto-ventrally a rather short and weak 



* Cf. tho rinnark on Euconchoecia Chierchiae below. 

 Zooloii- bidnig. Uppsala. Siippl.-Bd. I. '2 



