322 The American Naturalist. [April, 
Gadow, the former of which is discussed by Gétte. The two researches 
only agree in discovering a much greater complexity in the ontogeny 
of these vertebre than paleontology gives the least ground for suppos- 
ing to have ever existed in the adult types of extinct Teleostomous 
fishes. 
In his papers on primitive Edentata Dr. J. L. Wortman describes 
more fully than heretofore on new material, characters of the genus 
Psittacotherium Cope. He finds that it is armed with robust com- 
pressed claws, and that the foot is short and megatheroid in appearance 
He interprets the dentition in a new way, and then homologizes with 
it the dentition of the genera Hemiganus and Ectoganus. The teeth ~ 
formerly described as incisors in these genera he regards as canines. 
To these he adds Stylinodon Marsh, to form a family Stylinodontide. 
The genera Onychodectes and Conoryctes Cope he places in a family 
Conoryctide. Both he combines into a suborder Ganodonta of the 
order Edentata. 
Whether the interpretation of the dentition of Psittacotherium and 
Ectoganus is correct or not depends on the interpretation of the same 
parts in Calamodon. Some doubt must still remain as to this point, a 
doubt which I have always felt. It is certainly not unlikely that Dr. 
Wortman’s interpretation may turn out to be correct, and if true, a clear- 
ing up of the subject of the relation of these forms to the Tillodonta of 
Marsh will result. Accepting his view as correct, we have then a group 
having strong claims to being regarded as ancestral to the Edentata. 
This position I maintained as long ago as 1875, when (in the Report of 
the U.S. Geol. Geogr. Surv. W. of 100th mer., Vol. 1V) I included some 
of these forms (Ectoganus and Calamodon) in a suborder Tæniodonta, 
and suggesting its ancestral relation to the Edentata. I have not 
pressed this view recently for the reason above referred to. The name 
was, however, given, and it was applied to a group so far equivalent to 
Wortman’s name Ganodonta, that as matter of taxonomic rule it can- 
not well be displaced. His reasons for rejecting the name are that I 
referred two of the genera (Conoryctes and Onychodectes) to the Cre- 
odonta, which I still do; that I failed to recognize the affinities be- 
tween Calamodon and Stylinodon, which, however, I always have done 
so far as the imperfect description of Marsh would permit. Thus, in 
my Synopsis of Families of Vertebrata, AMERICAN NATURALIST, OC- 
tober, 1889, I place in the suborder Tzeniodonta, the two families 
Ectoganidae and Stylinodontidae. Wortman concludes also that the 
name must be rejected because founded in error. If this be true, it is 
