1<i2 TACrE SKOGSBERG 



are paired and are situated posteriorly in the body. Tn young specimens they are bag-shaped, 

 in mature specimens shaped like a bunch of grapes; see G. W. MOLler, 1894, pi. XL, fig. 27. 

 They gradually pass into the thin-walled o v i d u c t s (which are widened distally only in 

 exceptional cases); these emerge paired, in most cases on small genital lobes situated 

 in the corresponding places as the copulatory organs of the male. Two r e c e j:) t a c u 1 a 

 s e m i n i s are developed, one on each side; each receptaculum consists of a chitinous capsule, 

 which is sometimes sunk deeply in the body, but in most cases, however, projects freely (in the 

 genital lobe) and emerges close to the oviduct. No parts of the genital organs penetrate 

 between the lamellae of the shell. 



H e a r t always developed. 



r g a n s of sen s e: — Lateral eyes most fre(|uently well-developed, 

 less often more or less reduced, seldom c^uite absent; the number of ommatidia varying 

 greatly. — The n a u p 1 i u s or m e d i a n e y e situated rather deep down on the 

 forehead, always developed, sometimes ( Gigantocyfris) extremely large. Ventrallv close 

 to the nauplius eye there is a r o d - s li a p e d f r o n t a 1 o r g a n, often rather long, 

 sometimes very small (or even not developed at all?). — Some of the limbs have 

 sensorial bristles. 



Branchiae sometimes developed dorsally on the back of the bod v. 



The eggs are carried continuously after laying between the shell and tiic l)ack of the 

 liody until they hatch. 



Salt-water forms of moderate size or sometimes even very large (maximum length so 

 far found: 21 mm., Gigantocyfris). Most frequently more or less completely confined to the 

 l)ottom; sometimes, however, they belong entirely to the plankton. 



Special terminology: — Second antenna: — The spine at the base of the 

 natatory bristles of the exopodite is called ,, basal spine". 



Mandible: — It does not seem to be quite right to follow most writers in calling 

 the endite of the coxale a ,, masticatory process" since, at any rate as far as we know, it is not 

 used directly in dissecting food. In the present work it is called (except in the family 

 A-steropidae) simply endite. 



Seventh limb: — The bell-sha23ed segments distally on the cleaning bristles are 

 called „bells"; the most distal of these segments often ,,the end-tongue". Tlic comb-like 

 formations distally on this limb are called ,, end-combs". 



Historical*: — Some of the first publications about forms belonging to this group consist 

 merely of descriptions of species written in very general terms, based exclusively on the outei- 

 characteristics of the shell. But even the earliest writers on this subject made an attempt at 



* On aciciuiil c)l pmlViuiid (iifferences bctwcTii llu' A s I e r o p i d s and tin- other lornis In-longing to tlir 

 ?roup discussed here hoth in their morphology and oecology, the Ivnowledgf of the lirst-nanu'd grouii has developed in 

 a rather independi'i\l manner. Hecanse of this it seenn'd most convenient to me in the present treatise to discuss the 

 history r)f the iiivestiiration of the A s t e v o p j ,| s in a spi'rial ihapfiT togi'lhcp with oilier prohleins concerning 

 this gidiiji. 



