148 

 Gen. 39. AmphiaSCUS, G. O. Sars, 1905. 



Syn: Dactylopus, Claus (part. 



Diosaccus, Boeck (part). 



Stenhelia, Brady, Scott (not Boeck). 



Scliizopera, G. 0. Sars. 



Generic Characters. Body more or less slender, cylindrical in form, with 

 the anterior and posterior divisions not sharply marked off from each other. 

 Cephalic segment of moderate size and not very deep, rostrum well defined and 

 very mobile. Urosome with the genital segment in female imperfectly divided in 

 the middle, and scarcely dilated in front, posterior edge of all the caudal seg- 

 ments finely spinulose on the ventral and lateral faces. Caudal rami generally 

 short, apical setse slender. Anterior antennae of usual structure, and as a rule 

 composed of 8 articulations, 4 of which belong to the terminal part. Posterior 

 antennse with the terminal joint more or less dilated distally, and armed outside 

 with strong spines, at the tip with slender geniculate setse; outer -ramus very nar- 

 row, generally 3-articulate, middle joint quite short and in some cases imperfectly 

 defined. Oral parts normal. 1st pair of legs with both rami triarticulate, the outer 

 one much shorter than the inner, and in some cases resembling in structure that 

 in the genus Dactylopusia, inner ramus with the 1st joint slender and elongated, 

 seta of inner edge attached close to the end. Inner ramus of 2nd pair of legs 

 in male more or less conspicuously transformed, outer 2 joints confluent. Last 

 pair of legs foliaceous, with the proximal joint more or less expanded inside; 

 those in male much smaller than in female. 



Remarks. This genus was established by the present author in a recently 

 published paper on Pacific Crustacea 1 ), and on that occasion he called attention 

 to the fact that the genus Stenhelia of British authors does not by any means 

 answer to that genus as defined by Boeck, the latter being in reality very dif- 

 ferent, and closely related to, if not identical with, the genus Delavalia of Brady. 

 It therefore appeared necessary to substitute another generic name, to include 

 the species erroneously referred to Boeck's genus. The genus Scliizopera esta 

 lished by the present author to include a Pacific species, I am now disposed to 

 withdraw, as some of the characters upon which this genus was founded have 

 proved to occur also in certain species unquestionably belonging to the genus 

 Amphiascus. It may here be noted that several of the species referred by Claus, 

 and also by recent British authors, to the genus Dactylopusia ought likewise to be 

 included in the present genus, which seems to be very abundantly represented in 



"Pacifische Plankton Crustaceen" II, in Zool. Jahrbucher 1905, p. 380. 



