14 Bulletin 4J, United States A^atio/nil Museum. 



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

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

 supraoral lamina Avith its cusjis large, triangular, well separated; a small 

 pointed median cus^) sometimes jiresent 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 8^ ; 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, (jiage) to Iowa, both in 

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

 seems to be distinct from iaw^x/rw ji>ZrtH(r(, generally common in North- 

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

 anatomist, the first to study the lampreys of Caj'uga Lake. Specimens 

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



relriimijrMn niyi-niii, Rafinescjue, IcL. Oh., 84, 1820, (name pieoccu(jieii), Falls of Ohio. 

 Petromyson branchialis, GUntiieu, Cat., Vlil, 504, 1S70. 

 Ammocaetesiiiger, Jordan & Gilbert, Syuoi^sis, 9, 18S3. 



Ammocorles bmnclualiii, Jordan & ITordice, I.e., 2'J3, LStSG. Gacjk, in Wilder Quarter-Cent uia 

 Book, 43G, 1893. 



Class III. PISCES. 



(The Fishes.) 



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

 ed for life in the water, breathing by meaus 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; jjelvic bones present; exoskeletou 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 wudely 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, ChimcTeras 

 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— 

 Selaciiii, Hoi.ocEriiALi, Dipnoi, Chossopterygia, and Teleostomi. As 

 there are no North American representatives of the Dipnoi (Ceuatodus, 

 Lepidosikex, PHOTOPTEKUS),or of the Chossopterygia (Polypterus), 

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

 work. 



