GENUS PAXTOSTEUS. 181 



diafe between that of Catostomus proper and that of the subgenus 

 Dccadactylus. 



The genus was first indicated by Professor Cope in 1874, under the 

 name of Minomus, he supposing at the time that Catostomus insignis, the 

 type of Girard's Minomus, was a species with closed fontauelle. On 

 obtaiuing specimens of C. insignis, it became evident that such was not 

 the case, and the new name Pantosteus was proposed for the genus. 

 Pantostcus runs very close to Catostomus. two species referred to the 

 latter genus (C. discobolus and C. arceopus) being almost intermediate. 



Generic Characterizations. 



MINOMUS Cope, 1872. "I have proposed to adopt as valid (Proc. Amer. Phiios. Soc. 

 ISO) seven genera of this family. I will now add an eighth, which embraces 

 species which combine with 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 is seen in, Cydeptus, Raf., as I have already men- 

 tioned. In all the members of the family where I have examined it, this fontauelle is 

 quite open and of no doubtful proportions, and nowhere reduced to the slit so often 

 seen in Siluridce. In searching for the characters of Girard's so-called genera Minomus 

 and Acomus, I find that the type of the former, M. insignis, B. G., presents the character 

 above mentioned. I therefore adopt his name for the new genus, and add two new 

 species, M. delpliinus and M. lardus. Whether his two other species, M. plebdus and M. 

 clarkii, belong to it is uncertain as yet, but they have the same physiognomy." (CoPE, 

 Hayden's GeoL Sun\ Wyoming for 1870, p. 434, 1872.) 



PANTOSTEUS (Cope) Yarrow, 1876. " 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 uni- 

 versal among the suckers ; the only other exception being seen in Cydeptus, Raf., as he has 

 already observed. In all the members of the family that he has examined in this re- 

 gard the foatanelle has been found quite open and of no doubtful proportions, and is 

 nowhere reduced to the slit often seen in the Silurida3, unless it be in the Catostomus 

 discobolus. In searching for the characters of Girard's so-called genera Minomus 

 and Acomus, he expressed the view that the type of the former, M. insignis, Biird & 

 Girard, presents the character in question. This conclusion was based on a specimen 

 sent to the Academy of Natural Sciences from Washington, bearing that name. Hav- 

 ing since examined five specimens of the M. insignis, obtained by the geologists of this 

 fiuivey, he finds them to be true Catostomi as determined by the presence of the fon- 

 tanelle. It therefore requires a name, and he proposes for it that of Pantosteus. It 

 embraces P. platyrhynchus, P.jarrovii and P. virescens Cope of the present essay and P. 

 delpliinus and P. bardus, Cope, Hoyden's Report, 1. c." ( YARROW, Lieut. Wheeler's Expl. 

 W. 100/7* Mer. vol. 5, p. 073, 1876.) 



PANTOSTEUS Cope & Jordan, 1877. "Body oblong or elongate, with a short, sub- 

 quadrate dorsal fiu ; air bladder in two parts ; lateral line well developed ; fontanelle 

 obliterated by the union of the parietal bones." (JORDAN, Proc. Ac. JVaf. Sc. Phila. 

 1877, p. 81.) 



