942 The American Naturalist. (November, 
ide, as I had already proposed this name in the work above quoted 
(1875) before I was aware of the affinity or identity of the genera 
_Pelecopterus and Erisichthe. All this has been overlooked by Mr. 
_ Crook. ; 
Mr. Crook further states that only three genera, Portheus, Ichthy- 
odectes and Saurodon (Daptinus), belong to the family. But Hypso- 
don and Saurocephalus should not be omitted. He also observes that 
I gave the name Portheus because of the resemblance of the fishes it 
embraces to the bull-dog; and that the word does not occur in any 
Greek or Latin lexicon. Just why Mr. Crook thinks that Portheus 
has any relation to bull-dog he does not tell us, but if he will look in 
the Greek lexicon he will find that zope: means to destroy, and from 
this verb the substantive is easily derived. Finally the species of 
Ichthyodectes, regarded as new by Mr. Crook, and named J. polymi- 
erodus, is probably the J. arcuatus Cope.’ This species is one of several 
from this horizon which would have been figured long ago by me had 
not it been for the policy pursued by the present U. S. Geological ; i 
Survey. 
Mr. E. T. Newton, in an otherwise able article’ some years ago, 
resolved that the catalogue name Protosphyraena of Leidy should be 
used instead of Erisichthe. Apart from the fact that Leidy’s name 
was published without description, thus putting it outside the pale of 
recognition, the name was made to apply to two very different species, 
P. ferox and P. striata. P. ferox belongs to the genus called by me 
Erisichthe, while the P. striata belongs to another genus. According 
to the usual custom, the Leidyan name, if used at all, should be applied 
to the P. striata, since the P. feroz had been referred to another genus. 
This rule was, however, not followed by Mr. Newton, and Mr. Crook 
imitates him.—E. D. Corr. 
On the Permanent and Temporary Dentitions of Certain 
Three-toed Horses.—At a meetinglof the Philadelphia Academy 
held Oct. 4, 1892, Prof. Cope described the changes in the characters 
of the superior molars of the Protohippus placidus Leidy, resulting 
from age and wear, and the characters of the dentition of colts of 
Protohippus and Hippotherium. He pointed out that in stages of 
wear up to middle life the P. placidus is the Hippotherium gratum of 
Leidy, and that then the protocone fuses with the paraconule, and the 
‘Proceeds, Am. Philosoph, Soc., 1877, p. 177: Portheus arcuatus Cope, Cretaceous 
Vertebrata, 1875, p. 204 (not figured). 
“Quarterly Jour. Geol., London, 1877, p. 505. 
Pak ot 4 he ane E 
