Families of Ttleostean Fishes, 165 



Mouth small, toothless ; vertebras with strong 



p:irapophyse3 ; head and body covered with 



spiny scales 20, GonorhynchidcB. 



Mouth small, toothless; no symplectic; head 



and body naked 21. Cromeriidce. 



Suborder 11. O S T A R I P ii Y S I. 



Air-bladder, if well developed, communicating with the 

 digestive tract by a duct. Pectoral arch suspended from the 

 siiull; mesocoracoid arch present. Fins without spines, or 

 dorsal and pectoral witli a single spine formed by the co-ossifi- 

 cation of the segments of an articulated ray. The anterior 

 four vertebraj strongly modified, often co-ossified and bearing 

 a chain of small bones (Wcberian ossicles) connecting the 

 air-bladder with the ear. 



This is one of the most natural groups of the class Pisces, 

 although its members are so diversified in outward appear- 

 ance as to have been widely separated in the systems of 

 older authors. It is to Sagemelil* that is due the credit of 

 having first grouped, under ihe above name, the Characines, 

 the Carps, the Cat fishes, and the Gymnotids, the relations of 

 which had been realized to a certain exlent by Cope. But it 

 was not until the homology throughout the group of the 

 ossicula auditus, first described by E, 11. Weber in 1620, had 

 been demonstrated by Sagemehl that the justification for tlie 

 course here followed appeared in its full strength, as sucli an 

 agreement in tlie structure of so complicated and specialized 

 an apparatus can only be the result ot acommnnity of descent 

 of the families which are possessed of it. It is invariably 

 the anterior four vertebras that take part in the support of the 

 AVeberian apparatus. The first vertebra is mucli reduced; 

 its upper arcii is absent and replaced by the ossicles termed 

 claustrum and scaphium'\, the former being perhaps nothing 

 but the modified neural arch, which fill in the space between 

 the exoccipital and the neural arch of the second vertebra; 

 the princij)al piece of the apparatus, the tr/pus, variable in 

 form, is related to the third vertebra, of v.'hich it is regarded 

 as a modified rib; a fibrous ligament extends from the ante- 

 rior extremity or the tripus to the scapJiium, and in this 

 ligament is inserted the fourth piece, the intercalariam. The 

 various forms of this suborder also show a complete agree- 

 ment in the spinal nerves which pass through these ossicles. 



* Morphol. Jahib. x. 1885, p. 22. 



t For the uomenclalure of these ossicles, ef. Bridge and Haddon, Proc. 

 Roy. Soc. xlvi. 1889, p. 310. 



