(70) 
Class MARSIPOBRANCHII. 
Order HYPEROARTIA. 
Family PETROMYZONTID^l- (the Lampreys.) 
Genus AMMOCCETES , Dumeril. 
175. Ammocoetes niger (Eaf.) Jor. Small Black Lamprey. (M. V. 
349 ; Petromyzon niger Nelson 52.) 
Common in small streams in many places, ascending to spawn 
in the spring. Pecatonica R., Freeport. 
176. Ammocoetes argenteus (Kirt.) Jor. Silvery Lamprey. (M. V. 
349; Ichthyomyzon argenteus Nelson 52.) 
Probably more or less abundant through the state. 111. R., 
Pekin. 
177. Ammocoetes hirudo (Grd.) Jor. Leech Lamprey. (M. V. 350 ; 
Ichthyomyzon hirudo Nelson 52.) 
A species supposed to be the one to which Girard gave the 
name of hirudo is quite abundant in the Mississippi and lower 
Ohio. *Ohio R., at Cairo. 
* Where exact localities are given in the preceding paper, they are in nearly 
every case taken from specimens now in the Laboratory, collected by myself or my 
assistants. S. A. F. 
