GENUS MYXOSTOMA. 113 



and lips, although the species of Minytrema was inadvertently included 

 in it. The most important generic feature, the tricellular air bladder, 

 was Qrst noticed by Professor Cope. 



I have seen fit to change (he orthography of the name from Moxoatoma 

 to Mi/xostoma, in accordance with its apparent etymology. This change 

 is rather desirable from the fact that it tends to avoid confusion, the 

 name Moxostoma hav'ing been commonly used in connection with a 

 diflferent genus. 



The genus Myxostoma contains two well marked sections, typified 

 respectively by M. velatum and AL macrolepidotum, and characterized by 

 the form of the mouth and lower lip : that of M. veJata being as in the 

 genus Erimyzon; that of M. macrolepklotum being of the character most 

 common in this genus. 



Generic Characterizations. 



Moxostoma Rafinesqiie, 1820. — " Body oblong, compressed ; bead compressed, eigbt 

 abdominal rays, dorsal fin commo.ly longitudinal ; tail commo*nly unequally forked." — 

 {Ichthyologia Ohiensis, p. 54.) 



Teketui.us Rafinesque, 1820. — " Body elongate cylindrical or somewbat quadrangu- 

 lar, 9 abdo:ninal rays, dorsal fi'.s commonly small; tail equally forked. Au exten- 

 sive subgenus, to wbicb belong all tbe following species of Le Sueur: C.anrcolus, C. 

 macrolepidotus, C. longiroatrum, C. nigricans, C. vittatus, C. macuhsus, C. sucetta, besides 

 tbe C. teres and C. oblongus of Dr. Mitcbill."— (/c/i. Oh. p. 57.) 



Ptychostomcs Agassiz, 1855. — "In respsct to form of body and tbe structure and 

 position of tbe fins, this genus does not differ from Catostomus proper, but may be 

 distingiiisbed by tbe following structural peculiarities. Tbe lips are marked by trans- 

 verse ridges or folds, and bardly bilobed below ; tbey are not papillated as in Catosto- 

 mus proper. The generic name of this type is derived from this character of tbe lips 

 The head is shorter and stouter. Tbe dorsal is longer than it is high, but m tbe males, 

 it is longer in proportion than in the females. The anal of the male is also broader 

 than that of the female, and its lower margin lobed, while in the female it is trape- 

 zoidal and narrow. 



" The tcales are as large ou the anterior as on tbe posterior region of the body ; their 

 ver.ical diameter about as great as the longitudinal, so that the scales are nearly quad- 

 rangular, with rounded edges; the ornamental concentric ridges not longeruor broader 

 ui)on the posterior than upon the lateral and anterior fields; the radiating furrows few, 

 only one or two in the posterior field and one on each side limiting that fitld from the 

 lateral fields; those of the anterior field are more numerous, and yet not crowded. 

 Tube of the lateral line arising in the centre of radiation or farther back upon the 

 posterior field. 



" The pharyngeals are strong, their entire edge spreading like a wing, and that 

 spreading margin is separated from the symphysis by a deep emargination. The 

 teeth increasing rather rapidly in size from above downwards, are more apart from one 

 Bull. K M. No. 12—8 



