1878. ] —— Recent Literature. 81 
classes of vertebrates. Regarding segmentation in vertebrates as 
PROSET me invertebrates, our author considers the body-seg- 
of a vertebrate not as a single organ, but as the combination 
of a a neuromere arising from the ectoderm with the scleromere 
and myomere arising from the mesoderm, which arise indepen- 
dently of each other and are not in any way to be taken together. 
Such an antithesis between the neuromere and the other organ- 
segments do not exist in the segments of the Articulates. lher- 
ing also expresses the opinion that Semper’s revival of the hy- 
pothesis of Geoffroy St. Hilaire and Treviranus is a matter rather 
of personal convictions than a subject for scientific discussion. 
This hits the on the head. He also shows that in vertebrates 
the new segments of vertebrates, in early life, are terminal ; 
while the new A of articulates are interpolated between 
the penultimate and terminal segments o e law 
for articulates is not new to American ses though ay 
German and Swiss authorities are quoted in the present work. 
THE PRINCIPAL CHARACTERS OF AMERICAN CRETACEOUS DINO- 
SAURS.—Prof. Marsh, in the November number of the American 
Journal of Science and Arts, gives an account of the characters 
of several genera of saurians from.the Rocky Mountain region. 
This paper gives us. for the first time, the characters of their ilium 
and the mode of its junction with the pubis and ischium, and the 
structure of the feet and of the axis vertebra, all points of great 
value to comparative anatomy and palæont ology. He also extends 
already determined in nearly allied forms. e proposes for 
them all a new division of the p esis which he terms Satro- 
foda, with the following definition : (1) Fore and hind limbs 
nearly equal in size. (2.) Carpal and tarsal bones distinct. (3.) 
Feet plantigrade, with five bes on each foot. (4.) The precau- 
dal vertebrzee contain large cavities apparently pneumatic. a. 
The neural arches are united to the centrum by suture. (6.) Th 
sacral vertebrae do not exceed four, and each supports its own 
transverse process. (7.) The chevrons have free articular 
extremities. (8.) The pubes unite in front by ventral symphysis. 
(9.) The third trochanter is rudimentary or wanting. (10) The 
limb bones were without medullary cavities. 
We remark, with reference to the above definition, that it embod- 
ies the characters of a well-marked division of reptiles, but that 
many of the characters given do not have such significance ; or, 
in other words, do not possess the value which Prof. Marsh 
attaches tothem. Thus, while some of them should be retained, 
Nos. 1, 4, 5, 7 and 10 must be rejected. 
An important improvement over his previous essays is notice- 
able inthis one, in thatthe author gives a definition for the only new 
genus proposed, viz: Diplodocus, which is, therefore, a real addi- 
1 See Packard’s Guide to the Study of Insects. 
