14 Bulletin 4? ', United States National Museum. 



insertion of dorsal a little before middle of body ; both dorsals high, the first 

 1 \ in height of second ; anal tube conspicuous in the spring ; eyes moderate ; 

 supraoral lamina with its cusps large, triangular, well separated; a small 

 pointed median cusp sometimes present in the adult ; in half-grown speci- 

 mens the lamina forms a curved plate without distinct cusps; infraoral 

 lamina curved, with 5 to 9 feeble, bluntish, subequal cusps; about 3 bicus- 

 pid teeth on each side of mouth ; other buccal teeth simple. Head 8i ; 67 

 muscular impressions between gill openings and vent. Bluish black 

 above, silvery below. L. 6 to 10 inches. A small species ascending west- 

 ern streams in the spring in great numbers to deposit its spawn ; abundant 

 from Western New York (Cayuga Lake; Meek, Gage) to Iowa, both in 

 tributaries of the Great Lakes and the Ohio and Mississippi. Our species 

 seems to be distinct from Lampetra planeri, generally common in North- 

 western Europe. (Named for Burt Green Wilder, the distinguished 

 anatomist, the first to study the lampreys of Cayuga Lake. Specimens 

 from that locality are taken as types of L. wilderi. ) 



I'elromyzonnigrum, RAFINESQUE, Ich. Oh., 84, 1820, (iiame preoccupied), Falls of Ohio. 

 Petromyzon branchialis, GUNTHER, Cat., vm, 504, 1870. 

 Ammoccetesniger, JORDAN & GILBERT, Synopsis, 9, 1883. 



Ammocoetes branchialis, JORDAN & FORDICE, /. c., 293, 1886. GAGE, in Wilder Quarter-Century 

 Book, 436, 1893. 



Class III. PISCES. 



(THE FISHES.) 



The Pisces, or Fishes, may be defined as cold-blooded vertebrates adapt- 

 ed for life in the water, breathing by means of gills which are attached to 

 bony or cartilaginous gill arches, the gills persistent throughout life ; 

 having the skull well developed and provided with a lower jaw; the limbs 

 present and developed as fins, rarely wanting through atrophy ; shoulder 

 girdle present, furcula-shaped, curved forward below, rarely obsolete 

 or represented by cartilage; pelvic bones present; exoskeleton developed 

 as scales or bony plates or horny appendages or sometimes entirely want- 

 ing, and with the median line of the body provided with one or more fins 

 composed of cartilaginous rays connected by membrane, the fins rarely 

 atrophied. 



All recent writers on fishes agree that the Lancelets and the Lampreys 

 differ so widely in structure and development from the true fishes that 

 they must be regarded as forming distinct classes. Many writers go still 

 further, and remove from the class of fishes the Sharks, Skates, Chimeras 

 and Dipnoans. A smaller number remove the Ganoids, also. It seems to us, 

 however, preferable to regard these, with the True Fishes, or Teleosts, as 

 members of the single class of Pisces. 



The class Pisces may be conveniently divided into 5 subclasses 

 SELACHII, HOLOCEPHALI, DIPNOI, CROSSOPTERYGIA, and TELEOSTOMI. As 

 there are no North American representatives of the DIPNOI (CERATODUS, 

 LEPIDOSIREN, PROTOPTERus),or of the CROSSOPTERYGIA (POLYPTERUS), 

 these singular groups may be passed by without further mention in this 

 work. 



