Charles R. Stockard 485 
fact that were this a tongue or a tongue-like organ it would be a great 
anomoly in vertebrate anatomy; since none of the fishes, even the 
highest fishes, possess a tongue or even a tongue-like organ.” It is diffi- 
cult to understand how the authors could have gained this impression, 
for one cannot doubt that fishes have tongues and in some cases very per- 
fectly formed ones (cf. Parker and Haswell’s Text-book of Zoology, Fig. 
807, in which the tongue of the trout is shown and labeled). They 
would have been correct in stating that among fishes the tongue is not 
a conspicuous structure and that no fish has a protrusible tongue readily 
to be compared with the dental-plate of Bdellostoma. 
Again they mention that “The homology of this organ (referring 
to the dental-plate) with the vertebrate tongue has never been dis- 
cussed,” while as a matter of fact Neal, 97, three years before, studying 
the development of the hypoglossus muscles of Petromyzon, made the 
following statement: “I nevertheless consider it highly probable that the 
so-called tongue of Petromyzon is not the homologue of the tongue of 
higher vertebrates. This conclusion is based on the following grounds: 
1. The anterior segment of the M. parietalis ventralis remains the same 
in its relation in Petromyzon as in Ammocoetes, 1%. e., without relation 
to a tongue. 2. While the muscles of the tongue of higher vertebrates 
are derived from the anterior segment of the M. parietalis ventralis, 
which lies anterior of the hyoid arch, in Petromyzon the muscles of the 
“piston lingual ” extend throughout the length of the branchial region 
and terminate posteriorly in the cartilaginous pericardium. They are 
quite separate from the M. parietalis ventralis which lies lateral and 
ventral to them. I have stated this evidence of the difference in the 
relations of the tongue of Petromyzon and Gnathostomata lest one not 
familiar with these relations should think that an organ of the same name 
in these vertebrates should therefore be an homologous organ. As a 
matter of fact no comparative anatomist has attempted to homologize 
these two kinds of tongues.” This statement refers particularly to 
Petromyzon, but since Ayers and Jackson are discussing the Marsipo- 
branchii it seems pertinent in this place. They say that the dental-plate 
of Bdellostoma is homologous with the two pairs of accessory lingual 
dentigerous cartilages of Petromyzon. It appears that they had 
failed to see Neal’s work. On the other hand the work of Howes, 91, 
is cited in their literature list and indeed quoted on the first page of 
their paper, yet they have again overlooked or ignored the following re- 
mark he makes on pages 134-5: “If, as can hardly be doubted, the 
‘tongue’ of the Marsipobranchii is an organ peculiar to them and 
