ISOPODS OF NORTH AMERICA. 697 



Abdomen not abruptly narrower than the thorax; epimera large, dis- 

 tant; terminal segment truncate. 



Lateral parts of the thoracic segments expanded, discontinuous. 



Inner branch of the first pair of pleopods in the male, produced, 

 biarticulate, that of the second pair in the male triarticulate. Inner 

 branch of the uropoda terminating in a single, slender spine: basal 

 article broadly expanded inside. 



Legs rather short and thick, scarcely increasing in length posteriorly. 



HAPLOPHTHALMUS PUTEUS Hay. 



Haplophthalmus puteus HAY, Proc. U. S. Nat. Mus., XXI, 1899, pp. 871-872, pi. 

 LXXXVI, figs. 1-15. 



Localities. Wells in Indiana. 



"Male. Body elliptical, length about three times the breadth, dor- 

 sal surface strongly convex, covered with longitudinal rows of low 

 tubercles and scattered seta?. Segments of the person about equal in 

 length, the posterior pleural angle of all, except the first, more or less 

 produced backward. Pleura? of third, fourth, and fifth segments of 

 the pleon thin and directed backward and outward. Terminal seg- 

 ment of abdomen notched behind and with the postero- lateral margins 

 concave. Uropods exserted, short, outer ramus longer than inner; 

 both rami setose. Front margin of head very slightly produced. 

 Antenna 1 longer than the greatest breadth of the body; first and sec- 

 ond segments of medium length, third short, fourth and fifth long; 

 flagellum short, pinniform, composed of three very small, closely 

 articulated segments. Antenna? geniculate between segments four 

 and five. Antennules minute, composed of three segments entirely 

 concealed by the front of the head, sensory filaments five. Eyes 

 small, simple. Upper lip regularly rounded in front and with a 

 median triangular patch of setae. Mandibles large and powerful, 

 bearing on the inner surface a broad, ridged molar tubercle; on the 

 anterior surface, one or two delicate, branched sensory styles. The 

 cutting portion of the mandibles is different; that on the left consists 

 of two portions, an outer with four heavy teeth and an inner with 

 three much smaller teeth: the outer mandible has but one row of 

 three or four large teeth which, when closed, fit in the space between 

 the two rows of teeth of the mandible first described. The first max- 

 illa has both branches erect, the outer bearing five or six acute curved 

 teeth, the inner three delicate plumose flagelliform processes. The 

 second maxilla consists of two strap-shaped lamella? closely applied to 

 one another and bearing seta? at their ends. The maxilliped is a 

 broad, low, flattened plate, with straight inner and rounded outer 

 margins, and bearing at the tip two obscurely segmented setose proc- 



