ON NORTH AMERICAN ZOOLOGY. 



209 



inhabiting the rivers of Carolina, and the other those of New 

 Soutli Wales. There is a greater variety of forms, as well as a 

 greater number of species of fresh water percoidese in North 

 America than in any other quarter of the globe ; indeed no other 

 quarter possesses such an extent of fresh waters. 



Cottoidece. — This being a more northern family than the 

 preceding one, we find, as in the higher orders of animals, a 

 greater proportion of its generic foinns common to the New and 

 Old World; — the condition of the waters as well as of the land and 

 atmosphere of the arctic regions of the two hemisphei'es is 

 more alike than in the more temperate parallels. Prionotus and 

 /temitriptertis are the only two cottoid genera which frequent 

 the Atlantic coasts of America, and do not also occur in Europe. 

 On the north-west coast, however, there are three genera which 

 are unknown in the European seas, viz. hemilepklotus, blepsias, 

 and temnistia. The Mediterranean produces peristedioii and 

 /loplostethus, of which no species has been detected on the 

 American coast. Five genera are common to both sides of the 

 North Atlantic, as are also several species, viz. trigla pini, dac- 

 tylopterus voUtans, aspidophorus europcens, scorjiccna porciis, 

 undsebastes norvegiciis, all marine fish ; there are moreover some 

 fresh water cotti and gasterostei in America, which are with 

 great difficulty distinguishable from their European representa- 

 tives. The family contains in all about 170 species, of which 

 one-fifth are North American, and between one-fifth and one- 

 sixth European. 



Scicenoidece. — Thefish of this family, more closely related to the 

 percoidecehy external form than the preceding, are also intimately 

 comiected with them by internal structure. The scia;noidece are 

 more American than either of the preceding families, one-third of 

 the genera being proper to the Atlantic coast of that continent, 

 and several of tlie remaining genera being represented there by 

 one or more species. There are alsofouror five times as many spe- 

 cies in the North American seas as in Europe; while the intertro- 

 pical seas nourish four-fifths of the whole family. None are com- 

 mon to both sides of the Atlantic. Several of the American scicB- 

 noidecB make a remarkable grunting noise in the water, which is 

 thought by Cuvier to be connected with the cavernous recesses in 

 the skulls of fish of this family. The noise made by several of the 

 cottoidece when handled is evidently produced by the sudden 

 escape of a quantity of air from their distended branchial mem- 

 branes. The total number of ascertained species of the family 

 is about 260. 



Sparoidecc. — This family, of which 150 species are known, 



VOL. v.— 1836. p 



