212 CALIFORNIA ACADEMY OF SCIENCES. 



distal] y excavated to receive the propodus. Second pair of chelipeds 

 longer and more slender than the first, the carpus long and not distally 

 excavated. The three following pairs of pereopods are longer than the 

 chelipeds; dactyls very short and spinulous below. All the abdominal 

 segments rounded above. Tip of the telson truncated or broadly rounded. 



Type. 5. pacifica (HOLMES). 



This genus is intermediate between Atyephyra and 

 Xiphocaris as defined by Ortmann. 1 The latter genus, 

 according to Ortmann, contains besides the type, X. 

 elongata, the Ephyra ? eompressa of De Haan which Von 

 Martens had placed in Atyephyra and for which Miers 

 had constituted provisionally the genus Paratya. Mr. 

 Ortmann recognizes but one species of Atyephyra, viz., 

 Desmarestii (the Caridina Desmarestii of Joly), which 

 Brito Capello described as Atyephyra rosiana, making 

 the new genus Atyephyra to receive it. Desmarestii 

 being generically distinct from Caridina in the strict 

 sense becomes, therefore, the type of Atyephyra. Our 

 two species differ from A. Desmarestii in not having the 

 carpus of the second pair of pereopods distally exca- 

 vated, in having the anterior part of the carapace 

 rounded above instead of armed with a dentate carina 

 and in having a prominent suborbital spine. 8. Trewi 

 approaches Atyephyra, however, in having exopods only 

 011 the first two pairs of pereopods instead of the first 

 four as in pacifica. From Xiphocaris elongata both of 

 our specie's differ in having supraorbital spines, in the 

 less number of exopods, and in having the carpus of the 

 first pair of chelipeds excavated. They approach more 

 nearly X. eompressa (De Haan), for in that species 

 supraorbital spines are present, though there are exo- 

 pods on all the pereopods, and the carpus of the anterior 

 chelipeds is not hollowed out. 



1 Proc. Acad. Nat. Sci. Phila., 1894, p. 399. 



