GEOGEAPHIOAL DISTEIBDTIOK OF THE EEL. 631 



flexible and have remained in an entirely cartilaginous state. Still it is not necessary to prepare 

 the skeleton to determine the absence of ossification, for we can establish this easily in unskinned 

 specimens by the flexibility of the jaws. It is very remarkable that this modification of the 

 skeleton is not incompatible with healthy existence, and that it does not prevent the fish in which 

 it is found from attaining a very large size. 



" Those fishes in which ossification is absent are remarkable by reason of the great reduction 

 of the number of teeth, which, although the only parts which become hard by the deposit of cal- 

 careous salts, remain however much smaller than in individuals whose skeletons are completely 

 ossified. 



" We can thus understand how such specimens could present characters apparently specific, 

 and that they should have been considered by Kaup as types of new species. These considera- 

 tions have led me to reduce, on an extensive scale, the number of species in the family. 



" So, in the genus Anguilla, I find but four species : Anguilla vulgaris, occurring throughout 

 the northern hemisphere, in the New World as well as the Old; Anguilla marmorata and A. motva 

 of the Indian Ocean, and Anguilla tnegalostoma of Oceanica. 



"There are at least four distinct types, resulting from the combination of a certain number of 

 characters; but the study of a very large number of specimens belonging -to these four specific 

 types has convinced me that each of these characters may vary independently, and that conse- 

 quently certain individuals exhibit a combination of characters belonging to two distinct types. It 

 is therefore impossible to establish clearly defined barriers separating these four types. 



"The genus Anguilla exhibits, then, a phenomenon which is also found in many other genera, 

 and even in the genus Somo itself, and which can be explained in only two ways: Either these 

 four forms have had a common origin and are merely races, not species, or else they are distinct 

 in origin, and are true species, but have been more or less intermingled, and have produced by 

 their mingling intermediate forms which coexist with those which were primitive. Science is not 

 in the position to decide positively between these alternatives."' 



It is the disposition of American ichthyologists, at least, to accept the views of Dareste, and 

 to consider all the Eels of the northern hemisphere as members of one polymorphic species. 

 Giinther is inclined to recognize three species in North America: one the common Eel of Europe, 

 Anguilla vulgaris; one the common American Eel, Anguilla bostoniensis {rostrata), which he finds 

 also in Japan and China; and the third, Anguilla texana, described and illustrated by Girard, in the 

 " Eeport of the United States and Mexican Boundary Survey," under the name of A. texana, which, 

 he remarks, is scarcely specifically distinct from A. bostoniensis, from which it differs only in the 

 greater development of the lips, a distinction which seems to be imaginary. The distinction 

 between A. bostoniensis and A. vulgaris, as stated by him, consists chiefly in the fact that the dorsal 

 fin is situated a little farther back upon the body, so that in the former the distance between the 

 commencement of the dorsal and anal fin is shorter than the head, while in the latter it is equal 

 to or somewhat longer than it. This character does not appear to be at all constant. 



Geographical distribution. — Assuming the specific identity of the Eels of the Old and the 

 New World, the distribution of the common Eel may be defined somewhat as follows : In the rivers 

 and along the ocean shores of Eastern North America, south to Texas and Mexico, and north at 

 least to the Gulf of Saint Lawrence, but absent in the waters tributary to Hudson Bay, the Arctic 



'These conclusions of Dareste have a very mediseval ring. "Science" is certainly in the position to say that 

 neither of these hypotheses can be true. From the stand point of modern zoology, the common origin of the species 

 of Anguilla admits of no reasonable doubt. Between the four " species" of Dareste and their less sharply defined 

 races, no permanent difference exists. The name " species" certainly cannot be refused to forms having supposably 

 a common origin. — J. 



