228 Phthinobranchii 



the two bones. In those species which have bony plates in- 

 stead of scales, this bone has a deposit of bony substance or 

 ganoid enamel at the surface. This gives it an apparent 

 prominence as compared with other bones of the skeleton, 

 but it has no great taxonomic importance. Dr. Hay 

 unites the suborders Hemibranchii, Lophobranchii, and Hypo- 

 stomides to form the order Phthinobranchii (<f>6ivas, waning; 

 fipayx 05 ' giU)' characterized by the reduction of the gill-arches. 

 These forms are really nearly related, but their affinities with 

 the Percesoces are so close that it may not be necessary to form 

 a distinct order of the combined group. Boulenger unites 

 the Hemibranchii with Lampris to form a group, Catosteomi, 

 characterized by the development of inf raclavicles ; but we 

 cannot see that Lampris bears any affinity to the stickle- 

 backs, or that the presence of infraclavicle has any high 

 significance, nor is it the supposed infraclavicle of Lampris 

 homologous with that of the Hemibranchii. The dorsal fin 

 in the Hemibranchii has more or less developed spines; spines 

 are also present in the ventral fins. The lower pharyngeals 

 are separated; there is no air-duct. The mouth is small and 

 the bones of the snout are often much produced. The preopercle 

 and symplectic are distinct. The group is doubtless derived 

 from some transitional spiny-rayed type allied to the Percesoces. 

 The Lophobranchs, another supposed order, represent simply 

 a still further phase of degradation of gills and ventral fins. 

 Dr. Gill separates these two groups as distinct orders and 

 places them, as aberrant offshoots, near the end of his series 

 of bony fishes. We prefer to leave them with the other transi- 

 tional forms, not regarding their traits of divergence as of any 

 great importance in the systematic arrangement of families. 



The Sticklebacks : Gasterosteidae. - - The sticklebacks (Gaster- 

 osieidcz) are small, scaleless fishes, closely related to the 

 Fistulariida so far as anatomy is concerned, but with very 

 different appearance and habits. The body often mailed, the 

 dorsal is preceded by free spines and the ventrals are each 

 reduced to a sharp spine with a rudimentary ray. The jaws 

 are short, bristling with sharp teeth, and these little creatures 

 are among the most active, voracious, and persistent of all 

 fishes. They attack the fins of larger fishes, biting off pieces, 



