150 REPORT OF STATE GEOLOGIST. 



AMMOcacTES BRANCHiALis (Linn.). 



Mud Lamprey ; Brook Laynpretj ; Pride. 



Jordan, 1888, 7, 10; A. niger, Jordan, 1882, 8, 9. A. branchialis. 

 Jordan & Fordice, 1885, i, 293 



A small lamprey, not exceeding perhaps eight inches in length. Dis- 

 tance from the snout to the last giil-openiug contained in the total length 

 about four and three-fourth times. Dorsal iin beginning about the 

 middle of the animal and continuing to the tail, but deeply notched a 

 little in front of the middle. Anal fin deep just behind the vent, then 

 low until reaching the caudal. Sucking disk rather small, surrounded 

 Avith a fringe of long papillae. Horny piate above the mouth expanded 

 at each end into a distinct tooth. Below the mouth is a transverse row 

 of blunt, horny teeth. On each side of the disk are about three teeth 

 with double tips; the other discal teeth are simple, small and not 

 numerous. Between the gills and the vent are about sixty-five trans- 

 verse muscular grooves. The color is a bluish black, with the disk and 

 the belly paler. 



Distributed from Central New York to Minnesota and south to Ken- 

 tucky. The European species is regarded as identical. 



In Indiana this species has been taken at Indianapolis in White River 

 (1, '77, 46), Falls of the Ohio, Wabash River, Bloomington, Ind. (1, 

 '85, 410), Vernon, Jennings County. It is also given by Jordan in 7^, 

 No. 2, as an inhabitant of Lake Michigan. 



Too little is known concerning the habits of this little lamprey. It is 

 said to ascend small brooks in early spring for the purpose of depositing 

 its spawn. Where it passes the remainder of the year appears to be un- 

 known ; it probably inhabits the waters of the deeper streams. They 

 are often found clinging to stones and other bodies. They are of no 

 economic importance, but they would make good bait. 



Genus PfiTROMYZONT Litm. 



Lampreys with the horny plate above the mouth (supraoral lamina), 

 short and with only two or three closely approximated teeth. Teeth of 

 the disk numerous and arranged in arched rows radiating from the mouth. 

 Lingual teeth divided by a median groove into lateral halves. Dorsal 

 fin continuous, scarcely notched. The toothless young resemble Am- 

 vioccetes. 

 Two teeth on the supraoral lamina ; teeth of disk all simple- 



concolor, p. 151. 



Three teeth on the supraoral lamina; some of the lateral teeth of the 

 disk with two cusps. eastaneus, p. 151. 



