1886. | Embryology oF 
centrum to intercentrum and vice versa, while the chevron bones 
being continua, cannot do so. 
II. The neural arch actually does shift its position in Cricotus. 
In the posterior part of the caudal series it is principally on 
the intercentrum ; in the dorsal region it is on the centrum. 
From the preceding considerations I get the following impor- 
tant results : 
. The principal vertebral bodies in the Sphenosaurida! 
(Sphenosaurus and elydosaurus), if Fritsch’s descriptions be 
correct, are intercentra and not centra. 
I. It is probable that the true centra become extinct in the 
batrachian descendants of this family, so that the solid vertebrae 
of such Batrachia are intercentra, and not centra. 
III. The characters of Cricotus on the other hand point to the 
extinction or reduction of the intercentra as we find it in the 
pelycosaurian Reptilia, and point to the probability of the Embolo- 
meri being ancestors of the Reptilia, as I have already suggested.” 
IV. The Sphenosauridz (which must also include Sparagmites) 
are intermediate between the Rhachitomi and the Embolomeri, re- 
sembling rather the latter in the completion of the true centrum, but 
resembling the former in the incompleteness of the intercentrum. 
I note here that Dr. Credner? does not understand why I should 
have overlooked the discovery of the rhachitomous structure of 
Archegosaurus by Von Meyer forty years ago. I think any 
one who examines Von Meyer’s description and figures will find 
ample reason why one should not see the rhachitomous structure 
in them, without overstepping the bounds of scientific caution. 
And it is evident that European naturalists did not recognize this 
Structure, as they make no mention of it during those forty years, 
although specimens of Archegosaurus are abundant; but rather 
frequently referred Archegosaurusto the Labyrinthodontia, which 
are described as having the vertebrz undivided. 
I had hoped to have given before now engravings in quarto of 
these important forms, but the present U. S. Geological Survey 
having suspended my work, I am unable to do so.—Z&, D. Cope. 
EMBRYOLOGY.‘ 
THE DEVELOPMENT OF THE TOAD-FISH.—The development of 
the Batrachidze is not well known, as will appear from some 
the Statements in systemetic treatises. One author states that: 
The young of some or all the species fasten themselves to rocks 
y means of an adhesive disk, which soon disappears.” 
„It is the purpose of this notice to point out that the adhesive 
disk referred to above is of a wholly different nature and origin 
= that found in the lump-fishes and Gobiesocidz in which such 
Cope. NATURALIST. . $92. : : 
TERCAN spain 18 qs 37. ey 
Dende aus dem Plauenschen Grundes bei Dresden; Zeitschr. 
PORRE . .» Berlin, 1885, p. 721. pas 
Edited by Jonn A. Ryner, Smithsonian Insti tution, Washington, D. C. 
