AAO Scientific. Intelligence. 
modification of the vitelline matter undergoing the primary influences 
of fecundation, for they are also found in tissues which are undergoing 
development, and even in those which form a part of the adult 
organism. It is these which, by their juxtaposition in the Mammalia, 
give origin to the earliest and most important formation of the tissues of 
the germ, because the blastodermic membrane is formed at their 
expense; that is to say, that which will subsequently become the 
basis of the entire organism. It is true that by gradual conversion into 
cells they soon raise the blastodermic membrane to a higher degree of 
organization; but they reproduce it at a period when they are still 
simple granular spheres, and they then still enjoy all the properties of 
these spheres, so that after their incorporation they continue for a certain 
time to multiply by subdivision, as we shall show in a future memoir. 
2. Spondylosaurus; by M. Fischer pe WatpHeEtm, (Bull. Soc. Imp: 
Nat. de Moscow, tom. viii, 1845; L’Institut, No. 624, Dec. 1845.)—The 
fossil to which the name Spondylosaurus has been given, was found by 
M. H. Frears, near Stchioukino, on the banks of the Moskwa, in the 
Oolite formation. Only a few vertebree have been seen. The form 
and size of the vertebre appear to place the animal between the Plesi- 
osaurus and Ichthyosaurus. Their form is round, a little ovoid trans- 
versely. The anterior surface is concave and smooth ; the posterior & 
little less concave. They are rather broader than long, and nearly cy- 
lindrical, with the middle a little smaller than the ends. There are only 
two apophyses, dorsal and costal. A process extends from these apophy- 
ses and unites with the transverse apophyses. The latter are situated 
exactly at the middle of the vertebre and have a funnel shape ; the rib 
must therefore have had a rounded head, and articulated freely in this 
cavity, with a ligament attached to the process just mentioned. The 
name of this species alludes to this peculiarity. The specific name 
given to it, is Spondylosaurus Frearsit. 
3. Thoracoceras, a new genus of the family of Orthoceratites ; by M. 
Fiscuer pE Waxpueim, (L’Institut, No. 631, Feb. 4, 1846, p. 48.)— 
The genus Thoracoceras is distinguished by having the transverse septa 
concave, imbricate or distant, and not surrounding entirely the siphun- 
cle. The siphuncle is always marginal, sometimes thin, or appearing 
obliterated at the junction with the septa, and sometimes remarkably 
thick ; and it may be either spirally contorted or annulated, or covered 
with scales or leaves. [This genus appears to be identical with Con- 
rad’s Cameroceras, instituted in 1842.—Jour. Acad. Nat. Sci. viii, 267.] 
4. Fins of Fishes afford important characteristics.—Prof. Agassiz ob- 
serves as a result of some late investigations, that the characters drawn 
from the fins of fishes, hitherto almost entirely neglected, are ie 
important to Zoology and Paleontology. 
Pn, 
