ISOPODS OF NOKTH AMERICA. 



273 



This genus differs from Cassidina Milne Edwards and Cassldinella 

 Whitelegge, 6 in not having the palp of the maxillipeds with the second, 

 third, and fourth articles produced into lobes. 



ANALYTICAL KEY TO THE SPECIES OF THE GENUS CASSIDI8CA. 



a. Terminal segment of abdomen smooth. Outer branch of uropoda about one- 

 fourth as long as inner branch. Apex of abdomen truncate. 



Cassidisca lunifrom (Richardson) 



a'. Terminal segment of abdomen with three low transverse elevations as the base. 

 Outer branch of uropoda more than one-third bui, not quite one-half as long 

 as the inner branch. Apex of abdomen triangulate Cassidisca oralis (Say) 



CASSIDISCA LUNIFRONS (Richardson). 



Cassidina lunifrons RICHARDSON, American Naturalist, XXXIV, 1900, p. 222; Proc. 

 U. S. Nat. Mus., XXIII, 1901, p. 533. 



Locality. Great Egg Harbor, New Jersey. 

 Bod}^ oval, surface smooth. 



Head broader anteriorly than posteriorly, the antero-lateral angles 

 being produced in a lateral direction and form- 

 ing very acute angles. The eyes are situated at 

 the post-lateral corners of the head. The first 

 pair of antennae reach two or three joints be} r ond 

 the antero-lateral angle of the head; 

 flagellum six-jointed. The second 

 pair almost reach the posterior mar- 

 gin of the first thoracic segment; 

 flagellum consists of about eight 

 joints, the first four being large, 

 the last four small and setose. 



The first thoracic segment is well 

 fitted to the head, so that the ellip- 

 tical outline of the body is pre- 

 served. The segments are sub- 

 equal, with straight lateral margins. The epimera are not distinct 

 from the segments. 



The first segment of the abdomen is short. The terminal segment 

 is subtriangular, with apex truncate. The inner branch of the uropoda 

 is pointed at its extremity, and reaches the tip of the abdomen. The 

 outer branch is rudimentary, about one-fourth as long as the inner 

 branch. 



Gerstaecker (Bronn's Klassen und Ordnungen des Thier-Reichs, V, Pt. 2, Pts. 

 1, 2, 3, 1881, pi. vi, fig. 12a) figures the maxilliped of Cassidina typa Milne Edwards, 

 and shows the second, third, and fourth articles of the palp produced into lobes. 

 Specimens of Cassidina emarginata in the collection of the U. S. National Museum 

 have the maxillipeds with the second, third, and fourth articles of the palp also pro- 

 duced into lobes. 



& Austral. Mus. Mem., IV, 1901, pp. 201-246. 

 2858905- 18 



FIG. 283. -CASSIDISCA LUNI- 

 FRONS. 



FIG. 284. CASSI- 

 DISCA .LUNI- 

 FRONS. MAXIL- 

 LIPED. x 77|. 



