334 Dr. A. S. Packard on new North- American Phylhpoda. 



A. longicaudatus chiefly in the shorter maxillipeds, and much 

 longer, smooth telsou witli three instead of four median spines, 

 and in the smooth, finely spinulated caudal stylets, while the 

 carapace is longer. Number of segments behind posterior edge 

 of carapace 29; number beyond last pair of feet 11. Length 

 of body 1'78, of carapace along the middle "To; total length 

 1-00 ; length of tergal carina '50 ; distance from front end to 

 front edge of carapace "30 ; length of caudal stylets 1*05 inch. 



Two specimens from " Utah, J. S. Newberry, No. 1." Mus. 

 Chicago Acad. 



Ajnis (Kqualis, n. sp., ^ . — In this species the carapace is much 

 longer than in the preceding species, the eyes are larger, the 

 tubercle behind them is smaller, and the gills reach much nearer 

 the telson. Number of segments behind posterior edge of shield 

 23 ; number behind last pair of feet 11. Length of body I'lo, 

 of carapace along the middle '56, breadth 'oG ; length of tergal 

 carina '35 ; distance from front end of carina to front edge of 

 carapace "21 ; length of caudal stylets '75 inch. 



Two specimens from " Matamoras, Mexico, General Couch." 

 Mus. Chicago Acad. 



? . The telson has five median spines and is shorter, and the 

 stylets have more numerous and sliorter spines than in A. Xeic- 

 herryi. The underside of the telson is much smoother than in 

 A. longicaudatus^ and the outer gill of the fii'st maxillipeds is a 

 little longer and more acute. Number of segments beyond the 

 hind edge of carapace 25 ; number beyond the last pair of feet 9. 

 Length of body 1-07 ; length of carapace in middle 'oG, breadth 

 •46 ; length of carina "33 ; length from front end of carina 

 to front edge of carapace "23; length of caudal stylets '75; 

 diameter of egg-sac "24 inch. 



Thirteen specimens from " Matamoras, General Couch " and 

 " Kansas, No. 5," Mus. Chicauo Acad., and a specimen from 

 Yale j\Iuseum labelled "- Plains of Hocky Mts., No. 390." 



Apus Guildingiiy Thompson, Zool. liesearches, Jan. 1834, 

 p. 108, belongs to the same section of the genus as A. (vqualis ; 

 but the fom'th branch of the first maxillipeds is longer than in 

 any other species known to me, being represented as reaching 

 almost to the end of the caudal stylets. St. Vincent, West 

 Indies. 



To the third section of the genus belongs the European species 

 A. cancrlformis, and the following species from North India. 

 They difter from the North- American species in the longer cara- 

 pace, the smaller eyes, and round postorbital tubercle, the less 

 spiny telson, the more hairy caudal stylets, and the larger 

 hypostoma. 



A}>uti In'tn(d<i>/anu.^,n. !^\).j '^ . — Frontal doublure and hypo- 



