OF DENISON UNIVERSITY. 1 5 



this Stage was first encountered, it was supposed to be a Cypridopsis. 

 While working at its anatomy, a specimen with the markings charac- 

 teristic of Cypris Herricki was discovered. This led to an investiga- 

 tion of the larval history of the crustacean. 



These facts give us a very strong hint that the genus Cypris has 

 been evolved directly from the genus Cypridopsis. Should future 

 research show that all members of the genus Cypris have a Cypridoysis 

 stage, ^ the discovery would give much weight to the hint. And if, at 

 the same time the internal structure should prove to be similar, the 

 evidence would be conclusive. 



III. Ilyocryptus spiniff.r, Herrick, not the same as Ilyocrvp- 



Tus LONGiREMUS, Sars. 



In a recent j^aper'-' Professor Birge remarks that it cannot be 

 decided whether Ilyocryptus spinifer., Herrick, is identical with Ilyocryptus 

 longiremus, Sars. or not, because none of the specific characters of the 

 former are mentioned or figured. Evidently Professor Birge has not 

 seen a paper written by the author of the Final Report on Minnesota 

 Crustacea, the next year after that report was published f for in that 

 paper the author has not only fully described and figured Ilyocryptus 

 spinifer, Herrick, but he has also made comparisons between it and 

 three then known European representatives of the genus. For con- 

 venience, I quote the entire description : 



"The size varies gready, a full grown female with eggs in the 

 brood cavity is nearly 0.90 mm. long and 0.70 mm. high, while a 

 smaller female measures 0.65 mm. long by 0.44 mm. high. The 

 form of shell is nearest like that of /. acutifrons. the height being less 

 than in /. sordidus, and the angle between the ventral and posterior 

 margins less than in /. ai^iiis. The entire length of the post-abdomen 

 in the lar^^e female is 0.^6 mm. measured to the base of the caudal 

 stylets, of which length 0.168 mm. pertains to the claws. The width 

 of the post-abdomen is but 0.14 mm. Thus it is evident that the 

 proportions of the post-abdomen differ greatly from any of the 

 other species, it being very long and narrow. The terminal claws 



' It must be remembered that Cypris o'i'uvi Clau.s is a member not of the genus 

 Cypris, but of the genus Cypridopsis. 



2 List of Crustacea, Cladocera from Madison, Wis., 1891. p. 393. 



3 C. L. A^^-rr/rX'— Mud-inhabiting Crustacea. Bulletin of the Scientific Lab. 

 of Denison University. Vol.1, 1885; pp. 39-41 ; pi. IX, I'lti"^- i-3- 



