THE LJEECHES OF MINNESOTA 119 



behind the female pore, and both may lie dorsad of the nerve cord or 

 one pass beneath it. There is a large pyriform albumen gland, a short 

 common oviduct and a relatively short, thick vagina. 



A median and one or two pairs of lateral longitudinal furrows, 

 together with some less constant and minor ones, mark the ventral 

 surface of the lip. The transverse sulcus dividing the buccal chamber 

 from the pharynx is deeper than usual, which is perhaps correlated 

 with the entire absence of dentigerous jaws in this as in the last de- 

 scribed species. Although somewhat variable and irregular there are 

 typically about twelve prominent longitudinal pharyngeal folds. Nine 

 of these are in three groups of three each coalescing anteriorly at what 

 would be the position of the jaws in other species. Three, unusually 

 simple and frequently incomplete folds, alternate with these. The 

 stomach scarcely shows any indication of lateral pouches and the 

 posterior pair of caeca are remarkably short, scarcely one-half the 

 length of the intestine. 



On the dorsal surface the ground color varies from tawny olive 

 through olive and olive green to oil green, the green colors being nearly 

 pure in some examples, especially in those which are least spotted. In 

 others they are impure from the suffusion of brown or dusky pigments 

 in the deeper tissues, in extreme cases imparting to the entire dorsum 

 a brownish hue. The lighter greens appear most frequently toward 

 the anterior end and on the caudal sucker, but in many examples these 

 regions become dusky- Frequently a marginal rufous or orange stripe 

 is present, especially toward the posterior end, but it is seldom or 

 never so clearly defined as in H. plumbeus. The ventral surface is 

 gray, yellowish or light brown but always paler than the dorsum. 



There is a great range in the degree of maculation which, as com- 

 pared with H. marmoratis, is characterized by a greater boldness and 

 distinctness in this species. Perhaps the most typical condition is that 

 in which the dorsum of each complete somite is marked by eight or ten 

 irregular but somewhat quadrate black spots, most of which' are con- 

 fined to the limits of one annulus, but a few, especially toward the 

 margins, are larger and more irregular. In other cases the spots are 

 much more numerous and confluent so that the real ground color ap- 

 pears as lighter areas on the dark field. Still others are as nearly free 

 from spots as some examples of H. plumbeus. The ventral surface 

 bears fewer spots than the dorsal and not infrequently is quite immacu- 

 late. 



