Sliidirs 1111 rii;ifiiiij Osll'ai:<ji|b 1-11 



All representatives of this family presumably go through The number uf posi- 

 sevenpostembryonal moults. At any rate the number of moults is not subject to ""^''y'"'"' """'"- '" 

 variation in this family, a result that is of the greatest importance in judging of BrOOKS's law. '" '"'"''' 



Sub-order: Halocypriformes. /jniori/ijri/ormr^. 



Conchoecia elegans. 



All the individuals described and measured below were caught at the same time and 

 at the same locality, on the 1st. of Feb., 1911 off the west coast of Sweden, S. Koster, at a 

 depth of 125 m. 



Only two larval stages could be distinguished with certainty. 



General description of the larval stages: — 



Stage I : — 



Male: Shell: Average length, 1,74 mm. It is of about the same type as that of 

 the mature female; cf. fig. 5 in the special part. The shoulder ridge is somewhat less distinctly 

 marked. The r o d - s h a p e d organ is of about the same type as in the mature female, 

 shows about the same variation and projects almost the same distance beyond the first antenna 

 as in this sex. First antenna: The e-bristle is, as in the mature female, about twice as 

 long as the four other distal bristles; the latter are subequal or else the b- and d-bristles are 

 somewhat shorter than the a- and c-filaments; the b- and d-bristles are rounded distally and 

 somewhat narrower than the a- and c-filaments, and xmlike these, they are annulated; the bristle 

 on the second joint is straight. Second antenna: This is like that of the mature female; 

 the c- and d-bristles are developed; laterally and somewhat distally of the latter there is a rather 

 powerful peg, see fig. 9 of this species in this work. The sixth limb has the same number 

 of bristles as in the mature stage; of the bristles of the end joint the middle one is somewhat 

 longer than the tut;il length of the two distal joints, the two others are about a third or a 

 quarter shorter; the remaining bristles are more like those of the mature female than those 

 of the mature male. The s e v o n t ii limb has the definitive type. The j) e n i s is about 

 of the same type as shown in fig. J 7. ])1. 34, G. W . MilLLER, 1894. The f u r c a has seven claws, 

 which decrease fairly uniformly in length and strength the more proximally they are situated. 



F (> 111 a I (■: Shell: Average lengtli, 1,5 mm. It is of the same type as that of the 

 male in this stage. The rod -shaped organ and the limbs are about the same as in 

 the mature female. The f u r e a is like that ol the male in this stage. 



Stage II: — 



Male: Shell: Average length, 1,13 inin. It is relatively .somewhat higher than in 

 the preceding stage; length: height = about 2,25: 1. The shoulder ridge is scarcely developed 

 at all. The postero-dorsal corner of the shell has a point that projects rather less, but the latter 

 is furnished with secondary teeth as in the preceding stage. The rod - .s h a ped orga n 

 is somewhat more slender than in the j)receding stage. The first antenna has quite the 

 same type as in the female. The second antenna is the same as in the preceding 

 stage, but one of the c- and d-bristles is very small. Sixth limb: The three bri.stlcs of 

 the end joint have about the .same relative lengths as in the mature female; as in the last 



