500 Heterogenetic DevelopmeJit in Diaptomns. [May, 



The teeth of this species differ from those of " Coronatus " too 

 much to confuse the two. This species is of the naviis and 

 parens group, but the caudal stylets closely resemble tenuicornis. 

 Near Paducah, Ky. 



Cyclops modestus, sp. nov. 



Antennae remaining i6-jointed in all individuals seen, very short, formula 

 — <^ —'-i o — c/'6/c o t/'o u£. _ c/ ; antennules short jointed; fifth foot three-jointed, 

 with unequal spines; caudal stylets of moderate length, lateral set?e about half vv^ay 

 to base of stylet, three longest terminal setae subequal. 



This is a small species related to the preceding, but differs in 

 many respects, the form of the spermathaeca is oval. The ^'g^ 

 sacs are slender, elongate oval. Cullman county, Ala. 



Post-embryonal Development of two species of Daphnia. 



In a previous paper it was shown that the spine found on the 

 posterior portion of the shell in young and male individuals, in 

 all members of this genus, is a persisting embryonal character, 

 and its possible advantage to the economy of the animal was 

 pointed out. It was indicated that a recognition of the facts 

 brought out, would throw several species into synonymy. It is 

 my wish, in this paper, to illustrate the extent of the variations 

 passed through in the course of later development, by two exam- 

 ples, one of which has been but imperfectly described, while the 

 other is new to America. 



These two species differ from any known to me, though they 

 may possibly be found among some of Sars' numerous nominal 

 species. 



Daphnia longispina Herrick (Microscopic Entomostraca, 1877). 



This name was applied to the young, and in connection a figure 

 was given of a male with the spine on the head which, in the 

 female at least, was indicative of immaturity. The name is not 

 particularly appropriate, for the mature female is not evidently 

 ;spined. 



This name has been long applied to another form in Europe, 

 but apparently to an immature stage of another species, so that 

 it is really vacant. 



In a paper (Notes on Cladocera of Minnesota) in the Rep. of 

 Geol. Surv. of Minn. 1881, the post-imago is figured, and a variety 

 of the younger stage (a little distorted in the molt). I am now 

 able to complete the chain from the embryo to the post-imago (see 



