244 REPORT OF NEW JERSEY STATE MUSEUM. 



lamellae, all of same structure, rarely obsolete. Uropoda, whert 

 present, simple, lanceolate. Male more or less slender, perfectly 

 symmetrical, with cephalon evenly rounded in front, and all seg- 

 ments of mesosome sharply defined, those of metasome some- 

 times distinct, sometimes confluent. Last larval stage with 

 mouth simple, conic. Posterior antennre with flagellum quadri- 

 articulate. Legs of uniform structure. LIropoda with inner 

 ramus shorter than outer. Parasitic on decapodous Crustacea. 



A number of genera have been described. The greater num- 

 ber of species live as parasites in the branchial cavities of higher 

 crustaceans. 



Key to the Genera. 



a. Abdomen of female with lateral parts or pleural lamells not elongated or 

 digitate, but rudimentary or absent. probopyrus- 



aa. Abdomen of female with lateral parts or pleural lamellae elongated, digi- 

 tate. LEIDY.A. 



Genus PROBOPYRUS Giard and Bonnier. 



Probopyrus Giard and Bonnier, Bull. Scient. France Belg., (3) XIX, 1888, p- 

 S2)- Type Bopyrits ascendens Semper, monotypic. 



Female. — Body with neither side swollen. Abdomen with 

 six distinct segments, lateral parts of pleural lamellae not elon- 

 gate or digitate, but rudimentary or absent. Pleopoda present, 

 all biramous. All legs of both sides present. Uropoda wanting. 



Male. — Abdomen with segments fused dorsally, but defined on 

 lateral margin. Five pairs of small tuberculiform pleopods 

 present. Uropoda absent. 



Retiiarks. — Branchial parasites. One species in our region^ 

 parasitic on the common prawn. 



Probopyrus pandalicola (Packard). 



Plates 73, 74 and 75. 



Praurn Louse. 



Bopyrus pandalicola Packard, Zool. Students Gen. Readers, 1879. p. 308, text 

 fig. 262. No locality. 



