196 SMITHSONIAN MISCELLANEOUS COLLECTIONS [vor. 48 
The families, besides the Cyprinids, are the Catostomids, Cobitids 
and Homalopterids ;1 the four may be recognized by the following 
selected characters: 
The Catostomids or suckers have the upper margin of the mouth 
partly formed at the sides by the supramaxillary bones, the pharyn- 
geals are falciform and armed with a single comb-like row of 
numerous more or less compressed teeth; there is no palatal pad, 
and the air-bladder is either bipartite or tripartite. 
The Cyprinids or carp-like fishes have the upper margin of the 
mouth formed entirely by the intermaxillary bones, the pharyngeals 
are truly falciform and armed with few teeth in any row; there is 
a molariform pad behind the palate, and the well-developed air- 
bladder is generally bipartite, being divided into two chambers, 
an anterior and posterior, but sometimes tripartite, the posterior 
chamber itself being transversely constricted. 
The Cobitids or loaches have the upper margin of the mouth, as 
in the Cyprinids, formed entirely of the intermaxillaries, the pharyn- 
geals are only subfalciform and a single row of teeth is borne on 
a ridge-like margin; there is no molariform palatal pad, and the 
air-bladder is more or less reduced, disconnected from the stomach, 
divided into lateral halves enclosed in a bony capsule, and often 
open to the skin on the sides. 
The Homalopterids have the upper arcade of the mouth formed 
exclusively by the intermaxillary bones, the pharyngeal bones are 
most like those of the Cobitids and the teeth in considerable number 
and uniserial; there is no palatal molariform pad, and the air- 
bladder is suppressed or rudimentary and representative of the an- 
terior chamber of the Cyprinoid bladder, divided into lateral halves 
which are enclosed in a bony capsule.” 
The geographical distribution of these groups is noteworthy. 
The Catostomids are almost peculiar to North America, the only 
extra-American species being several Siberian forms of the genus 
Catostomus and one generic type peculiar to eastern Asia (My-o- 
cyprinus). The Cyprinids, as will be more fully explained further 
*The four families were first named and defined as now understood by 
Gill (Proc. Acad. Nat. Sc. Phila., 1861, pp. 6-9), and have been adopted by 
American ichthyologists generally and by Smitt (1895); the Cyprinide, Co- 
bitide and Homalopteride were recognized by Fatio (1882) and the four 
groups have been ranked as subfamilies by Boulenger (1808 and 1904). 
*A remarkable generic type .from Borneo (Gyrinochilus) with double 
branchial apertures, a mouth resembling a tadpole’s and a small but free air- 
bladder was described in 1902 by Vaillant. It is the type of a peculiar family, 
Gyrinochilide, and not a member of the family Homalopteride. 
