studies on marine Ostracods 187 



Penis: — Although it is subject to considerable variation, this organ seems to be 

 formed on the same fundamental type within the whole of this sub-family. It is oval, very 

 strongly musculated and in most cases of considerable size. Distally it is split in the shape 

 of tongs; the ventral leg of the tongs is often larger than the dorsal one and is rounded distally; 

 the dorsal leg, which is moved by powerful muscles, varies in shape; in most cases it is sickle- 

 shaped, curved ventrally and rounded distally. When the dorsal leg of the tongs is pressed 

 against the ventral one it is situated most frequently medially to the latter. Large or small 

 glands are often to be found in the penis. In addition there are also at different places on this 

 organ large or small groups of short bristles. As a support a powerful chitinous skeleton is 

 developed, varying somewhat in different species. The dorsal leg of the tongs articulates to 

 the dorso-distal part of this skeleton. 



F u r c a: — In some, presumably the majority, of the species of this group this organ 

 agrees in males and females, in others it shows weak or sometimes even not inconsiderable 

 sexual dimorphism. — The type of the lamellae varies somewhat in dift"erent forms, but seems 

 to be fairly uniform within each genus. The number of the claws is also subject to a rather 

 considerable variation; in some genera it seems to be quite imiform, in a number of forms it 

 varies somewhat, even within the species; usually the number varies between four and twelve; 

 sometimes, however, as in the genus Crossophorus, a somewhat larger number is found. In some 

 species main claws and secondary claws can be distinguished, in others it is impossible to carry 

 out this division. The armament of the claws seems to be very similar; at least in the species 

 belonging to this group that were examined by me there was very little variation shown in this 

 respect. Each claw is armed ventrally along the greater part of its length with two rows of 

 teeth situated rather close together, one row running somewhat laterally, the other somewhat 

 medially; on the posterior claws the teeth are somewliat weaker than on the anterior ones, 

 otherwise they are of about the same size and shape as each other, conical, pointed distally, smooth, 

 and pointing obliquely ventrally-distally. The distal teeth in the medial row of the distal (= first) 

 claw are, however, exceptions ; these teeth differ from the others partly because they are considerably 

 stronger, partly because they are displaced dorsally and point almost straight distally; see fig. 24 

 of Cypridina ( Macroci/pridina) castanea. The distal part of the claws is sometimes smooth, some- 

 times the teeth continue right out to the point of the claws; this condition is, however, often some- 

 what variable even within the species. Dorsally the claws are most frequently furnished with fine 

 hairs or else almost smooth. Between the claws andbasally on them there are no long, stiff bristles. 



The upper lip is large and more or less strongly helmet-shaped. Numerous glands 

 open on it; the glandular field varies very much in t}^e, often more or less distinctly tripartite. 

 — Similar in males and females. 



The rod -shaped organ, median eye and lateral eyes vary in 

 development and type. 



Gills are found, but only exceedingly seldom (C ypridina Hil(jendorliV>. W..MrLLER, J). 



Special terminology: — In a number of cases when, on account of striking agree- 

 ments both with regard to number and situation, I thought I could carry out a safe 



