1885.] Geology and Paleontology. 879 
my essay I state that twelve more or less complete crania of Didy- 
modus are in my possession. I now add that most of them were 
in my possession, and were objects of frequent mete eas by me, 
for five or six years before my publication in aanry : 
On p. 29 of his brochure, Mr. Garman sa 
“3. The skull is unsegmented ; the lines of segmentation, so- 
called, sais partly accidentals which are not alike on the two sides 
of the skull.’ 
To this it must be replied that the lines of segmentation cer- 
tainly exist, and that they are alike on the two sides of the skull 
“6. The Fig. 4 of the plate should be reversed in direction, the 
prolonged anterior portion in the figure should be turned back- 
wards from the interorbital region, thus bringing what in the fig- 
ure serve as orbits behind the postorbital processes. 
ave several perfect skulls of this species, including the 
one represented in ig. I, where the characters are readily seen, 
the supposition of Mr. Garman that I have reversed the specimen 
represented in Fig. 4 is simply curious; and as he derives his in- 
formation from a plate, one is also surprised at the lack of caution 
exhibited i in making the assertion 
e Ichthyotomi, as based on these skulls, have not been 
separated from the Selac 
The suborder Ichthyotomi was thus defined in my paper (p. 
581): “ A basioccipital bone and condyle. Occipital ? pterotic 
and frontal bones distinct. Supraorbital (or nasal) bones present,” 
r. Garman gets over this definition by denying the existence 
of the segmentation, which, as we have seen, nevertheless exists ; 
and by ignoring the presence of the basioccipital bone and 
condyle. This would indeed be the muzzle of the skull, were the 
direction of Fig. 4 reversed, as proposed by Mr. Garman. As 
the characters above given are proven to exist, I must still regard 
the genus Didymodus as presenting a type of skull quite different 
m the true Selachii. 
I now add a few comments on other points in Mr. Garman’s 
ee On p. 21 of his essay Mr. Garman gives five references 
to the publications where he claims that I have called the 
Chlamydoselachus anguineus, Didymodus anguineus.” I have, 
however, never proposed or used this name at the places cited, 
or elsewhere. On p. 28 it is stated that I have never published 
my conclusion that these two genera are distinct. This w. 
done in the AMERICAN NATURALIST, 1885, pp. 236-7. F og Vaia a 
new name is proposed as a substitute for Didymodus (p. 30), 
because the latter is supposed to have became a’synomyme in 
another connection. Were this the fact, I should still retain as 
unused the name Didymodus, by which the form is now known ; 
but as it has not yet been positively shown to be distinct from 
some of the various genera of this group already proposed, the 
action of Mr. Garman is at least premature—Z. D. Cope. 
