The Soft-finned Teleostei 367 



So in the division Catosteomi an excellent example is 

 furnished in the freshwater stickleback, of a primitive and 

 comparatively simple organization, of progressive advance 

 in defensive armature when some members became marine, 

 of added advance when other and allied genera passed 

 seaward permanently, and of final weird modification along 

 lines of protective simulation and defence, in those that 

 have become condensed and highly modified shore or ocean 

 dwellers. 



Of the soft-finned teleosts there remains a heterogene- 

 ous assemblage, the constitutent families of which will 

 doubtless in time be referred to other and appropriate al- 

 liances. This assemblage has variously been called the 

 Percesoces, Percomorphi, or Mugiliformes, and includes 

 the garpikes, sandeels, flying fish, mullets, etc. Technical- 

 ly the families are the Ammodytidae, Atherinidae, Mugili- 

 dae, Polynemidae, Chiasmodontidae, Sphyraenidae, Tetra- 

 gonuridae, Stromateidae, Ophiocephalidae, and Anabanti- 

 dae. Some of these are treated of below; of the remainder 

 it seems best to the writer to leave most of them till more 

 wide and exact details are secured regarding them. But 

 the presence of one or more dorsal fin-spines in many of 

 them, indicates that transition from soft-finned to spiny- 

 finned types has been a gradual process, and one that several 

 lines of families may have passed through. 



The Atherinidae or Silver-fishes consist of some 15 

 genera and 70 species, the simplest types of which, and 

 the richest in species, are Atherina and Chirostoma. 

 Atherina and the allied genus Rhamphognatlms are first 

 recorded from the Upper Eocene to Miocene marine rocks 

 of S. E. Europe, and mainly from the Monte Bolca deposits. 

 But the existing species of Atherina are either freshwater, 

 or anadromous, or marine. Chirostoma has been shown 

 by Jordan, Snyder, and Meek to include a large assemblage 

 of species native to and very abundant in the lakes of 

 central Mexico. "Another small species, very slender and 

 very graceful, is the brook Silver-side, Lahidesthes sicculus, 

 which swarms in clear streams from Lake Ontario to Texas" 

 (255:217). But migration seaward, during late Cretace- 

 ous or more likely early Eocene times, of species of Ather- 



