2'34: North American Species of Petrol nyzoniidoe. 



Habitat. — Streams of Wisconsin and Indiana. Probably 

 throughout the Mississippi Valley. 



This little species is very abundant in the spring in many 

 streams of Southern and Central Indiana and in Southern Wis- 

 consin. Its distribution outside of these regions is unknown ; 

 but it will probably be found in all parts of the Upper Missis- 

 sippi Valley. Part of the numerous specimens before us are 

 from Big Prairie Creek, a tributary of the Peckatonica River 

 near Monroe, Wis., collected by Mr. Winfrecl Copeland. Other 

 specimens are from the streams about Bloomington, Indiana. 

 All are about eight inches in length. 



This species ascends the streams in spring, and is then found 

 in the little brooks and spring runs in some abundance. Later, 

 it disappears. We have never seen its larva, nor any specimens 

 taken in summer or fall. 



This is unquestionably the Petromyzon nigrum, carelessly de- 

 scribed by Rafinesque. 



It may be that it is Le Sueur's P. lamotteni, known only from 

 a drawing of Le Sueur, published after his death. But this 

 drawing is either unfinished or inaccurate ; and while the denti- 

 tion figured looks somewhat like that of the present species, the 

 coloration is that of P. marinus. We think that P. lamotteni 

 must be regarded as unidentifiable. The possibility of the iden- 

 tity of Ammocoetes borealis and Ammocoetes mpyptera with the 

 larva of this species, has been elsewhere discussed. 



We have carefully compared our specimens with descriptions 

 and figures of the European species, especially with those given 

 in Day's Fishes of Great Britain and Ireland. We can detect no 

 differences whatever, and are therefore compelled to record our 

 specimens under the name of Ammocoetes branchialis. Should 

 comparison of specimens show that real differences exist, a new 

 name must be given to the American species, as the name niger 

 has been already used in this genus. 



