Gobioidei, Discocephali, and Tasniosomi 471 



the development of three or four inarticulate rays (or even less) 

 in the front of the dorsal fin is sufficient to ordinarily differen- 

 tiate a given form from another with only one or two such. Cer- 

 tainly the difference between the constituents of a disk and 

 any rays or spines is much greater than the mere development 

 or atrophy of articulations. Not those who consider that the 

 manner of depression of spines, whether directly over the follow- 

 ing, or to the right or left alternately, are of cardinal importance ; 

 for such differences, again, are manifestly of less morphological 

 significance than the factors of a suctorial disk. Nevertheless 

 there are doubtless many who will passively resist the propo- 

 sition because of a conservative spirit, and who will vaguely 

 refer to the development of the disk as being a ' teleological modi- 

 fication,' and as if it were not an actual fact and a develop- 

 ment correlated with radical modifications of all parts of the 

 skeleton at least. But whatever may be the closest relations 

 of Echeneis, or the systematic value of its peculiarities, it is 

 certain that it is not allied to Elacate any more than to hosts 

 of scombroid, percoid, and kindred fishes, and that it differs in 

 toto from it notwithstanding the claims that have been made 

 otherwise. It is true that there is a striking resemblance, espe- 

 cially between the young almost as great, for example, as 

 that between the placental mouse and the marsupial Antechi- 

 nomys but the likeness is entirely superficial, and the scientific 

 ichthyologist should be no more misled than would be the scien- 

 tific therologist by the likeness of the marsupial and placental 

 mammals." 



Suborder Taeniosomi, the Ribbon-fishes. The suborder Tazni- 

 osotni (raivia, ribbon; (roo^o/, body), or ribbon-fishes, is made 

 up of strange inhabitants of the open seas, perhaps aberrant 

 derivatives of the mackerel stock. The body is greatly elongate, 

 much compressed, extremely fragile, covered with shining 

 silvery skin. The ribbon-fishes live in the open sea, probably 

 at no very great depth, but are almost never taken by collectors 

 except when thrown on shore in storms or when attacked 

 by other fishes and dragged above or below their depth. When 

 found they are usually reported as sea-serpents, and although 

 perfectly harmless, they are usually at once destroyed by their 

 ignorant captors. The whole body is exceedingly fragile; 



