GEOlil.'AI'llH'AI, DISTIMI'.CTION OK TIIH HKL. 631 



flexible ;md have remained in an entirely cartilaginous slate. Still it is not nece>sary to prepare 

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

 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 si/.c. 



"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 haul 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. mowa 

 of the Indian Ocean, and Anguilla megalostoma 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 Homo itself, and which can be explained iu 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 beeu 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." 1 



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 rulgaris; one the common American Eel, Anguillo bostoniennin (roxtnitfi), which he finds 

 also in Japan and China; and the third, A>i</nillti ft.nuui, described and illustrated by Girard, in the 

 " Report of the United States and Mexican Boundary Survey," under the name of A. texnna, which, 

 he remarks, is scarcely specifically distinct from .1. hi>f<tonieiinix, 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 chicliy in the tact 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 tin 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 river- 

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

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



'These Conclusions of Dareste have a \n\ UK dhevul ring. "Scienrr" is orrtainl) in the poMtinii to say th:it 

 neither of tlie>e hypotheses eau In- Inn-. From the stand point "f modem /oology, the common origin of the species 

 of Anguilla admits of no reasonable doubt. Between (be four " species" of Dareste and their lesn sharply defined 

 races, no permanent dift'ei. me exists. The name " species" certainly cannot be refused to forms having supposably 

 a common origin. J. 



