528 Illinois State Lahoratorii of Natural History. 

 Haemopis lateralis (Say). 



Hirudo lateralis Say ('24). 

 Macrobdella valdiviana Pliilippi ('72). 

 Semiscolex terreslris Forbes ('90). 



Diagnosis. — VII /; 5 and /; 6 mid VIII /; 1 and d 2 are fully 

 developed, so that VII is quadriamiulate and VIII quinque- 

 annulate. The male pore is on annulns 34 (XI ^6), the 

 female on 39 (XII d 6) ; the vagina and atrium extend to the 

 anterior part of XIV; the ovaries lie between the female- 

 pore and ganglion XII. 



General Description. — Many of the characters of this large- 

 leech have been described by Forbes ('90). It reaches a size 

 much larger than H. numnoratis, some examples of the- 

 terrestrial variety from Illinois measuring as contracted 

 alcoholic specimens nearly 8 in. in length and f in. wide. 

 The smallest specimen in the collection measures 38 mm., 

 the largest 190 mm., in length. A medium-sized individual 

 from which the drawings Avere made, measures : — 



Total length, ....... 



Length to d pore, ...... 



Width at d" pore, 



Greatest width (just anterior to 17th nephridiopore). 



Width at anus, ..... about 



Diameter of posterior sucker, 



Depth at d' pore, ..... about 



Depth at last nephridiopore, 



Depth at anus, ...... 



Living aquatic examples which I have watched assume the 

 attitudes and shapes described for //. marnwj-atis, but 

 H. lateralis is much more slender and capable of much 

 greater elongation. The greatest width is further back 

 (about XXIII), from which point the body tapers gently 

 forward. Compared with H. marnwratis the ventral surface 

 seems flatter, the dorsal more abruptly, but still gently, 

 arched, and the anterior region more terete. As in that 

 species the surface of the body is perfectly smooth, without 



