592 General Notes. (June, 
these are modifications suffered by fresh-water genera, are not 
shared by their marine relatives, and appear to be necessary to 
the existence of sedentary forms, as characteristic of fresh-water 
organisms. The wide distribution of a form introduced by float- 
ing timber is not probable until its developmental history has 
changed also. 
Tue BATRACHIA! oF THE PERMIAN BEDS OF BOHEMIA, AND THE 
LABYRINTHODONT FROM THE Biyort Group (Inpra).2— In these 
contributions we find important additions by eminent palzontol- 
ogists to the knowledge of the stegocephalous Batrachia of the 
regions named. In Dr. Fritsch’s volume we have the continuation 
of an extensive work which we have noticed at various times in the 
NATURALIST as the successive parts appeared. We have to add, 
on this occasion, our renewed commendation of the care and de- 
tail with which Dr. Fritsch continues to develop the subject, and 
our praise for the admirable plates which accompany the text. 
The species treated of are those which belong to the larger forms 
of the Rhachitomi, together with some of the intermediate types, 
such as the Dendrerpetonide. Of the greatest interest are two 
new genera of the order Embolomeri, Chelydosaurus and Sphe- 
nosaurus, where the additional vertebral centrum, entire in the 
type of the order (Cricotus), is divided into three segments, two 
lateral and an inferior. This is a curious discovery, especially as 
Sphenosaurus has hitherto been regarded as a reptile.’ It also 
has an important bearing on the value of the order Embolomeri, 
which Dr. Fritsch is disposed (p. 4) to question. He thinks that 
the embolomerous vertebral structure is confined to the caudal 
region in the genus Cricotus, although I have figured it in the 
lumbar and cervical region of that genus, and described it as 
found in the dorsal* region. Dr. Fritsch reached this conclusion 
because he finds that in Archegosaurus the caudal region is em- 
bolomerous, and the dorsal region rhachitomous, His discovery 
of the persistence of the embolomerous condition in the dorsal 
ion of Chelydosaurus and Spl might have suggested 
to him the correctness of my observations on Cricotus. I add 
here that in Eryops, in which the dorsal vertebrz are rhachito- 
mous, the caudal vertebre are not embolomerous. So Archego- 
saurus stands alone in this respect. This determination of the 
characters of Archegosaurus by Dr. Fritsch is very useful to 
in palzontologists, as it has hitherto been very imperfect- 
ly described. I have stated that there are vertebre of this type 
1 Fauna der Gaskohle in d. Kalksteinen d. Permformation Böhm Von Dr. An- 
ton Fritsch, B. 11, Heft 1; Praag, 1885. ' i R a 
2 The Labyrinthodont from the Bijori group. By R. Lydekker, Mem, Geological 
apid of India, Ser. rv, Vol. 1, 1885. iiss . eae 
These two genera should form a second family of the Em i cterized 
as above, which I call the Sphenosauridee, TEI 
_ “Proceedings Amer. Philosoph. Society, 1884, P. 29. 
