422 BULLETIN 54, UNITED STATES NATIONAL MUSEUM. 



ASELLUS INTERMEDIUS Forbes. 



Asellus mtermedlns FORBES, Bull. 111. Museum of Nat. Hist., No. 1, 1876, pp. 

 10-11. UNDERWOOD, Bull. 111. State Lab. Nat. Hist., II, 1886, p. 358. 

 RICHARDSON, American Naturalist, XXXIV, 1900, p. 297. 



Localities. Found in hill country of southern Illinois, under stones 

 in small streams. 



Body oblong-ovate, about three times as long as wide, 2 mm.: 7 mm. 

 Head wider than long, 1 mm.: 1 mm., with the anterior margin 

 straight. Sides of head entire, with a small 

 lobe on either side near the base. E3 T es small, 

 composite, and situated close to the lateral mar- 

 gins, halfway between the anterior and the 

 posterior margins. The first pair of antenna? 

 have the basal article large and somewhat di- 

 lated; the second article is half as wide as the 

 first and about as long; the third article is a 

 little more than half as long as the second. The 

 flagellum is composed of nine articles and ex- 

 tends to the middle of the fifth article of the 

 peduncle of the second pair of antenna?; The 

 second antenna? have the first three articles 

 short and about equal in length; the fourth arti- 

 cle is about as long as the first three taken 

 together; the fifth is one and a half times longer 

 than the fourth. The flagellum is composed of 

 about fifty articles and extends a short distance 

 be3 T ond the posterior margin of the seventh thoracic segment. The 

 maxilliped has a palp of five articles. The palp of the mandibles is 

 composed of three articles. 



The first segment of the thorax 

 has the lateral margins entire, 

 with the anterior angle not devel- 

 oped and the epimeral lobe large 

 and conspicuous and placed an- 

 tero-laterally. The second, third, 

 and fourth segments have the 

 lateral margins entire, with the 

 antero- lateral angles well devel- 

 oped, and the epimera small and 

 almost inconspicuous and placed 

 antero-laterally. The fifth segment has the anterior part of the lat- 

 eral margin produced iira well-defined lobe, with the epimeron large 

 and conspicuous and placed about the middle of the lateral margin, 



FIG. 474. ASELLVS INTERME- 



Dirs. x 7. 



PIG. 475. ASELLUS INTERMEDIUS. o, FIRST LEG. 

 x 39. b, ABDOMEN WITH URPODA. x lit. 



