184 



Artedi established it in 1738 with the following characters : — 

 Gill-membrane containing six distinct bony rays ; head larger 

 than the body, depressed and acute. Two dorsal fins ; the an- 

 terior one composed of flexible spines. Ventral fins small, hav- 

 ing only four soft rays. Skin scaleless.* 



He places in the first rank the fresh water species having two 

 spines on the head, of which C. gohio is the type, being the 

 only one known at that time. Next the species with more spines 

 on the head, including not only the salt water species having a 

 smooth skin instead of scales, but two others which have since 

 become, one the type of the genus Aspidophoriis^ the other, the 

 type of the genus Callionymus. Artedi himself went thus 

 beyond the limits of his genus by placing in it the two last 

 species, as their body is covered with scales. 



Linnaeus t alters Artedi's genus by giving as the only charac- 

 ter for it, " a spiny head broader than the body." Linnaeus 

 went further ; he transposes the species and places at the head 

 C. cataphractus, the type of the genus Aspidophoriis, of later 

 date, and which Artedi placed at the end of the genus Cottus. 

 His third species belongs now to the genus Batrachus, and the 

 fourth to the genus Platycephalus. The C. gohio is the last. 



Fabricius| followed the example of Linnaeus. Cuvier§ 

 calls the primitive type of the genus Cottus, C. gohio, from 

 the fresh waters of Europe, in which have been since dis- 

 tinguished several species which were formerly confounded. 

 Cuvier, following Artedi, describes first the fresh water, and 

 next the salt water species. But when the celebrated ichthy- 

 ologist wrote the history of this genus, he did not find it 

 necessary to separate generically these two groups, although he 

 had already pointed out their principal differences. There were 

 only two fresh water species known, and that imperfectly. 



Now that their number is considerably increased, and the study 

 of them has become somewhat more difficult, it- seems proper to 

 subdivide the genus Cottus of the difl^erent authors in the follow- 

 ing manner : — 



* Genera Piscium. 



t Systema Naturte, ed. xii. 



t Fauna Grcenlandica, 1780, 8. 



§ Histoire Naturelle des Poissons, vol. iv. 1829, pp. 142, 150, 



