PLECTOSPONDYLI CYPRINIDAE P. PLATYRHYNCHUS. 673 



The species is dedicated to Chas. E. Aiken, of Colorado Springs, an 

 industrious naturalist, who has made a number of interesting discoveries in 

 various departments of zoology. 



One specimen; Pueblo, Colo.; Chas. E. Aiken. 



CATOSTOMIDAE. 



PANTOSTEUS, Cope. 



Professor Cope, in 1870, purposed to adopt as valid seven genera of 

 this family ; but, in 1872, he stated his belief that an eighth should be added, 

 which should embrace species combining the characters of Catostomus proper, 

 a complete union of the parietal bones, which obliterates the fontanelle so 

 universal among the suckers; the only other exception being seen in Cycleptus, 

 Raf., as he has already observed. In all the members of the family that he has 

 examined in this regard, the fontanelle has been found quite open and of no 

 doubtful proportions, and is nowhere reduced to the slit often seen in the 

 Siluridce, unless it be in the Catostomus discobolus. In searching for the 

 characters of Girard's supposed genera Minomus and Acomus, he expressed 

 the view that the type of the former, M. insignis, Eaird and Girard, presents 

 the character in question. This conclusion was based on a specimen sent to 

 the Academy of Natural Sciences from Washington bearing this name. 

 Having since then examined five specimens of the M. insignis, obtained 

 by the zoologists of this survey, he finds them to be true Catostomi, 

 as determined by the presence of the fontanelle. It therefore appears that 

 this genus requires a name, and he proposes for it that of Pantosteus. It 

 embraces the following species : P. platyrhynchus, P. jarrovii, and P. vir- 

 escens, Cope, of the present essay; P. delpMnus and P. bardits, Cope, Hay- 

 den's report, /. c . 



PANTOSTEUS PLATYRHYNCHUS, Cope. 

 PLATE XXIX, FIGS. 3, 3. 



M inomus platyrhynchus, COPE. Proc. Am. Phil. Soc. Phila., 1874, 134. Id., Plagop. 

 & Ichthy. Utah, 1874, 8. 



This Catostornoid is of very elongate form; the depth of the body at the 

 dorsal fin entering the total length seven and two-fifths times. The head 

 is short and wide, with expanded and depressed muzzle ; its length enters 

 43 z 



