504 Illinois State Laboratory of Natural History. 



borbood of Philadelphia they are most frequently found in 

 meadow brooks, adhering to stones, or attached to frogs and, 

 during the spring, to toads. They frequently enter the shells 

 of living mussels, which they probably attack. During the 

 spring at least they are voracious blood-suckers, and along 

 the Delaware Eiver congregate at points where fish are 

 cleaned and the waste thrown into the water. 



ICHTHYOBDELLID^. 



The collection contains several specimens of a small 

 species of Piscicola and another probably of Piscicolaria, 

 both parasitic on several species of small fishes. The 

 material is not sufficiently well preserved to permit of 

 determination or description. This family is further repre- 

 sented only by 



ACTINOBDELLA gen. nov. 



Generic Characters. — The head small, not explanate ; the 

 posterior sucker large, hemispherical, with a marginal circle 

 of slender processes ; the complete somites with six secondary 

 annuli of unequal size. 



Actinobdella inequiannulata sp. nov. 



Diagnosis. — A median series of papillae on annuli b 3 and 

 b 5 ; annulus b 5 the longest, b 4 the shortest, in complete 

 somites; male orifice at XI/XII, the female at XII b4; 

 acetabular papillae about thirty, provided with adhesive 

 glands. 



General Description. — The single specimen representing 

 this species is of small size ; the total length is 9.7 mm., the 

 greatest width 1 mm., and the diameter of the posterior 

 sucker about 1.8 mm. The sexual organs are very incon- 

 spicuously developed, and it is possible that the species may 

 reach a somewhat larger size. 



The form is slender (PI. XLIII., Fig. 8), with the margins 

 of the body parallel for almost its entire length, but suddenly 

 contracted posteriorly to constitute the narrow pedicle of 



