76 THE LIMITS OF THE CLASS OF FISHES. 
Dipnoi, Pisces, Elasmobranchii, Dermopteri, Leptocardii and the 
Mammalia.* 
Subsequently, in a most important special memoir on the classi- 
fication of fishes, Prof. Cope + (if I understand his views) recog- 
nized (as classes) six groups of Vertebrata; Mammalia, Saurop- 
sida (birds and réptiles), Batrachia, Pisces, Dermopteri, and 
Leptocardii. After enumerating these groups, he adds: ‘‘ These 
six classes of Vertebrata appear to be well established.” 
Three classes among Fishes.—After a careful survey of the field, 
the author had independently, several years ago, arrived at the 
same conclusion as Prof. Cope respecting the old class of fishes, 
but had neglected to announce them except in conversation with 
others engaged in like pursuit, and in lectures. He had, however, 
somewhat inclined to the recognition of the Elasmobranchiates 
as a class, but considers such at present inadvisable and perhaps 
uncalled for by the evidence ; like Prof. Cope, he cannot agree with 
Prof. Hackel in the separation of the Dipnoans from the class 
Pisces, the relations of that fornt with Polypterus and other univer- 
sally recognized Ganoids being more intimate than those between 
such Ganoids and the typical fishes. The number of classes recog- 
nized as confounded under the common designation of fishes will 
then be three, viz :— 
I. PISCES. 
SYNONYMES, AS CLASSES. 
< Pisces, Artedi, 1738, Linné, 1735-1754 (incl. Cete). 
os Ianné HSG, ob p fentora etc.) 
. e, 1825 
chthyoderes Aehihyoders, oir: te pda Tatralle 1825. 
ae proper, an 
> Ganoids, 
> Selachians, ‘gee 1857. 
> Pisces. 
> Dimen sain 1866. 
1868 
Cope, 
shes part., TAT plur. 
* Corr Œ. D.) Synopsis of the xtinct Batrachia and Reptilia of North America, 1869, 
_ p-3; Trans. Am. Phil. Soc., v, 
+ Cope (Edward Drinker), PAMBA i the Systematic Relations of the Fishes. 
(Contributions on the Ichthyology of the eal Antilles, $I.) <Transactions of the 
same memoir with the same ppo is oe in 
: seen 1871 (vol. 5, pp. 579-593, and in the Proceedings of the American 
Advance ement t of Science, aara (1872) pp. ee but without the pr 
