STATE GEOLOGIST. 



245 



length I'o'o cm. For this species the name macrothrix pauper is jpro 

 visionally offered. (Plate VIII, fig. I.) 



(Fig. 6.) 



MACROTHRIX TEKUICORJ^IS, Kurz. 



(Fig. 6.) 



The description given by Kurz is very full and agrees very well. The 

 peculiar arrangement of the movable spines at the margin of the 

 valves is characteristic. I have observed that this species forms an 

 ephJppiuni. Miiller says destinctly of the series of genera including 

 Macrothrix, Drepanothrix, Lafhonura, Bosniina, Acantholebris and 

 IliocryptuSy " Testae abjecfce corporis, nullo ephippio, ova hiherna 

 ohtegunt.'' 



Bosmina is little related to the Lipicodaphnidce and, however it may 

 be with regard to other species, in M, tenuicornis an evident ephippium 

 is formed in much the same way as in Ceriodaphnia. In Daphnia this 

 egg-cover is produced by an alteration of part of the inner layer of 

 the shell which becomes turgid and secretes a thick coating. The 

 ephippium simply extends over the brood-cavity, being marked off 

 from the rest of the shell by the median suture of the valves. In 

 other Daphnidce and in Macrothrix nearly the whole of the valves are 

 thus modified. The shell of M. tenuicornis is normally smooth, but in 

 the ephippial female, that portion of the inner layer of the shell 



