16 NEW YORK STATE MUSEUM 



larged; bMccal disk small, with few teeth which are never 



tricuspid. 



The genus Lampetra is best distinguished from Pe- 

 t r o m y z o n by the structure of its so called maxillary tooth, 

 which has the fonn of a crescent-shaped plate with terminal 

 cusps and, sometimes, an additional median cusp. In P e - 

 t r o m y z n this bony plate is short and contains* two or three 

 teeth which are very closely placed. 



4 lampetra wilderi (Gage) 

 Small Black Lamprey; Prkle 



Lampetra wilderi Gage, in Jordan & Evermann, Bull. 47, U. S. Nat. Mus. 



13, 1896. 

 Petromyzon nigrum Rafinesque, Ich. Obien. 84, 1820. (Name preoccupied). 

 Ammoca-U'S nUjer Jordan & Gilbert, Bull. 16, U. S. Nat. Mus. 9, 1882. 

 Ammococtcs hranchialis Jordan & Fordice, Ann. N. Y. Ac. Sci. 293, 1886; 



Gage, in Wilder Quarter-Century Book, 436, 1893. 



The high dorsal fin is divided into two parts by a deep notch. 

 Several of the teeth on the side of the buccal disk are bicuspid 

 and the rest simple. The mandibulary plate is nearly straight 

 and has eight or 10 cusps of nearly equal size. The length of 

 the head including the gills is contained four and three fourths 

 times in the total. There are 67 muscular impressions from gills 

 to vent. In the spring a prominent anal papilla is present. The 

 head is larger than the space occupied by the gill openings and 

 is contained eight and one third times in the total; the depth, 14 

 times. The eyes are large; the mouth moderately small. The 

 lips are conspicuously fringed with papillae. The teeth change 

 considerably with age; young examples have no median cusp on 

 liic maxillary i)late. 



This lamprey is bluish black above, the lower parts silvery. 



Tlic brook or mud lamj)rey, also known as the small black 

 lamj>r< y. is found in the Great lakes region, the Ohio valley and 

 Die upper Mississij)pi valley. It occurs also in Cayuga lake, 

 New York. According to Jordan it ranges west to Minnesota 

 and south to KMilucky. It grows to a length of 8 inches. Dr 

 Jordan considers 11 identical with the common brook lamprey 

 of EurojK', .\. It r a n ( li i a 1 i s. 



