682 Gobioidei, Discocephali, and Tzniosomi 
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 im 
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 Antecht- 
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 Tzniosomi, the Ribbon-fishes.—The suborder Teni- 
osomt (raivia, ribbon; ca@pa, 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; 
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