2l8 THE CHICAGO ACADEMY OF SCIENCES. 



Illaenus harrisi, n. sp., pi. xvi, figs. 1-3. 



Description. Cephalon short, large, nearly semi-circular 

 in outline, strongly convex, anterior and lateral margins slightly 

 recurved to form a narrow, slightly projecting, lip-like border. 

 Dorsal furrows rather strongly impressed, especially between 

 the eyes, elongate, extending nearly to the anterior margin 

 and terminating in pit-like depressions. Eyes large and promi- 

 nent, sub-crescentiform in outline, about three times as long 

 as high, convex both longitudinally and vertically, a little 

 oblique, the posterior extremity '-being a little higher than the 

 anterior, the centers situated above the middle of the total 

 height of the cephalon and much nearer the posterior than the 

 lateral margin ; eye-lobes convex, extending in a nearly hori- 

 zontal direction from the dorsal furrows ; the eyes strongly 

 protuberant with a conspicuous, broadly-rounded furrow be- 

 neath them upon the free cheeks. Free cheeks of moderate 

 size, posterior limb of the facial suture curving backward and 

 downward from the posterior extremity of the eye, the anterior 

 limb extending downward and forw r ard with a slightly concave 

 curve and intersecting the anterior margin of the cephalon 

 nearly in front of the eye, it then continues around the anterior 

 border upon the ventral side just back of the margin, the sutures- 

 from the opposite sides being continuous anteriorly. 



The characters of the thorax and pygidium have not been 

 observed. 



The dimensions of a cephalon, the type specimen, are: 

 length 32 mm., width 54.5 mm., convexity 29.5 mm. 



Remarks. This is not a common species and has been ob- 

 served only from Bridgeport in the Chicago area. In the elongate 

 dorsal furrows and projecting lip-like margin of the cephalon it 

 resembles /. insignis, but it differs from that species in its much 

 shorter cephalon and in its more strongly protuberant eyes 

 and eye-lobes. In its proportions it more nearly resembles /. 

 chicagoensis , but it may be distinguished from that species by 

 its elongate dorsal furrows, its projecting border and its more 

 prominent eyes. The nearest ally of /. harrisi seems to be 7. 

 springfieldensis, but the eyes are more prominent than in .that 

 species. 



The name is given in honor of Mr. G. F. Harris, of Chicago, 

 who collected the type specimen and presented it to the Walker 

 Museum of the University of Chicago. 



Locality. Bridgeport, Illinois. 



