1883.] NATURAL SCIENCES OF PHILADELPHIA. 157 



I. Inner face just above superior tooth much narrower than 

 anterior or posterior faces. 



a. An external marginal expansion. 

 Width at fourth tooth equal length of bases of superior three 

 teeth ; an external bevel below first tooth ; large ; S. posticus. 

 Width at fourth tooth considerably less than length of bases of 

 superior three teeth ; a bevel below base of first tooth causing 

 ala to be more distinct ; large ; S. laminatus. 



Ala not projecting ; width less than length of bases of superior 

 three teeth ; no bevel below first tooth ; smaller ; S. reddingi. 

 aa. No external ala. 

 Bone very narrow ; teeth spaced ; larger ; S. hairdi. 



II. Inner face just above superior tooth deep, equaling anterior 

 and posterior faces. 

 No external ala ; bone narrow ; S. arciferus. 



Squalius posticus Cope. Semotilas posticus Cope, Proceeds. Amer. Philos. Society, 

 1S70, p. 541. 



The original specimen is from Idaho. Onl}' a fragment of two 

 others are known. 

 Squalius laminatus Cope. OUgohelns luminntus Cope, loc, cit., 1870, p. 541. 



Originally founded on a single fragmentary pharyngeal bone. 

 A complete right-hand bone with all the teeth, found hy Mr. 

 Wortman, shows that this is as large a species as the G. postica^ 

 but of more slender proportions. 

 Squalius reddingi Cope, sp. nov. 



This species is founded on pharyngeal bones of individuals of 

 smaller size than those which represent the others mentioned in 

 this list. They represent a fish of the average dimensions of the 

 Pogonichthys insequilohus of California. The five teeth occupy 

 as much length as the style, and the apex is as long as the bases 

 of four teeth and an interspace. The apex is flat, and its inner 

 face is convex, and as deep at the base as one-half the width. The 

 e:Sternal alar expansion is slight but distinct, and originates 

 opposite the third tooth from below. The stj'le is not recurved. 



Measurements. m. 



Length on tooth series, •02() 



Length of tooth series, ..... '012 



Length of apex from teeth, . . . . 'Oil 



Width of bone at middle, "005 



