868 The American Naturalist. [October, 
which he, as usual, calls the lower Wasatch, (again in defiance of the 
rules) thus assuming that a genus of this group is common to the two 
formations, an assumption only to be made on far better evidence than 
is here offered. He next states that the name of the Puerco genus 
Periptychus Cope is“ preoccupied,’ but does not point out how or 
where. Scudder’s Index shows that a division (not a genus) of 
Lepidoptera has been called Periptyches, which is not preoccupation. 
The entire proceeding is an attempt to make something out of noth- 
ing and is unworthy of a place in a scientific Journal. 
The next genus mentioned is called Parahyus Marsh, which name 
was given in 1876. Osborn has regarded it as identical with Achz- 
nodon Cope, 1873, and no characters have been assigned which will 
distinguish them. The next name is Homacodon, which was given by 
Marsh without generic diagnosis in 1872. Two “new species” are 
named, but not described, but they are supposed to be introduced to 
science by figures of two astragali! The author asserts that the genus- 
which I described, also in 1872, under the name of Pantolestes, includes. 
species of * Homacodon.” As the type of Pantolestes is from the same 
horizon as Marsh’s specimens, it is probable that Homacodon is a 
synonym of that genus. If so, the superior molars are quadritubercular,. 
since Marsh so figures them in the present paper. It is, therefore 
necessary to give the tritubercular form from the older Wasatch horizon 
another name. For this genus, whose type is the Pantolestes brachy- 
stomus Cope, I propose the generic name of Trigonolestes. The proper 
description of the Homacodon vagans by Marsh in 1872 would have 
prevented the reference to the same genus of the Wasatch forms in 
1884. 
The next genus proposed is Nanomeryx, which is defined. The type 
and only species is called .N. caudatus, but is not described, except by 
the statement that it is half as large as the Pantolestes (Homacodon)- 
vagans, and by reference to figures of the inferior end of the tibia, and 
the astragalus. Rather hard lines for paleontologists who shall here- 
after desire to identify the species! We next reach the so-called genus 
Helohyus, which Marsh on a previous occasion alleged to be identical 
with Phenacodus. He does not repeat this statement in this paper, but 
says that it is suilline and therefore a member of another order, 
Two figures show that the two forms are also very distinct as to dentition, 
The name was originally proposed by Marsh in 1872 without generic 
diagnosis, and no diagnosis is given now, so that the field is still open 
to any one who may be able to properly characterize it. The abortion 
of another generic name given by himself by its union with 
“ Helohyus," is a step made by the author in the right direction. 
