Dr. A. S. l*jn-k;inl on ncir Xorf/i-Anicricun Phyllopoda. 333 



Ar<»i>iJ».i:. 



Tlu' kuown species of Apiu may be for convenience divided 

 intt» three sections, characterized in ])art by tlie lengtli of tlie 

 shieUl, or carapace, tlie hiii^hcst forms havinj^ the shortest cara- 

 pace ; those with the lonijest shichls, as the European ^ly^^i- 

 cancriformis, approximating in this and other characters to the 

 genus Lepidurus. 



Section a com})rises A pus longicaudatus^ Lucasanus, Neio- 

 herryi^ and probably domiiujensis. 



Section h comprises Apus aqiudis and (luiJduuju. 



Section c comprises -.-1. cancrifonnis and hiinalayanus. 



Apus longicaudatus^ Leconte, Ann. N. Y. Lyceum. — Prof. 

 Dana's type specimen, which is now very imperfect, was labelled 

 " Rocky Mountains, near Long's Peak." Four specimens 

 from "Texas, J. IL Clark, No. 3." Three specimens from 

 " pools near Yellowstone river, Dr. Hayden, No. 6." ^lus. 

 Chicago Acad. Both sexes occurred, the females having eggs. 

 James's A. ohtusatus (Long's Expedition) is probably this spe- 

 cies. A. numidicus, Lucas, from Algeria, in the form of the 

 carapace seems to be allied to A. lougicaudatus. 



Apus Lncasanus^ n. sp. — S closely allied to A.longicaudatus. 

 The frontal doublure rather longer than in longtcaudatus, and 

 hypostoma a little smaller ; maxillipeds shorter and smaller, 

 and telson longer than in the preceding species, with three 

 median spines above ; anal stylets less spiny. Number of 

 segments behind posterior edge of shield 33 ; number behind 

 the last pair of gills (including telson) 13. Length of body 

 (excluding caudal stylets) '94, of carapace along the middle 

 •37 ; total length of carapace '48 ; length of tergal carina '24 ; 

 distance from anterior end of carina to front edge of carapace 

 •16 ; length of caudal stylets '57, being a little over half the 

 length of body ; breadth of shield '40 inch. 



Six specimens in a bottle labelled " Kansas, No. 5," and con- 

 taining thirteen ? A. mqualis. Mus. Chicago Acad. They 

 cannot be distinguished from St. Lucas specimens. 



? . Carapace longer than in ^ , and caudal stylets not so 

 heavily spined. Number of segments behind posterior edge of 

 shield 29 ; number behind last pair of feet 11. Length of body 

 80, of carapace along the middle -30 ; total length of carapace 

 ■40 ; length of tergal carina '25 ; distance from front end of 

 carina to front edge of carapace •IG (stylet broken) ; diameter 

 of egg-sacs '09 inch. 



One specimen from " Cape St. Lucas, John Xanthus, No. 4." 

 Mus. Chicago Acad. 



Aptis Newherryi^ n. sp., ? . — This fine species differs from 



