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Nova Acta Academie Nature Curiosorum. 489 
limits of our system of living animals? and where shall we arrange the 
Lizards and the Crocodiles which in truth are neither Lizards nor Croco- ~ 
diles? Withsuch animals /ptychus also lived. It is evident from this 
how rich is the calcareous schist of Solenhofen in types new, but by no 
means improbable, whicl may happily enlarge the boundaries of our 
system.”’ Dr. Meyer rejects as altogether untenable Germar’s hypo-~ 
thesis that these shells belonged toa fossil Lepas, and that of Bourdes 
that they were the jaws of a fish; and combats at considerable length 
the opinion of Dr. Riippel, who regards them as the opercula of a shell 
in outer form resembling an Ammonite. To the animal of this shell, in 
the aperture of which crushed specimens are not unfrequently found, 
Dr. Meyer rather suspects them to have served as food. The character 
of the strata in which they are found is treated of at some length ; and 
an appendix adds two new forms to those previously described in the 
paper itself. Three plates are occupied with the figures and details of 
these several forms. 
The fourth and last section comprehends the descriptions of several 
*« New Fossil Reptiles of the Saurian Order ;”” an order in which the 
authour states that he has met with so much that is peculiar that he 
believes himself to be in a condition to give a new systematic arrangement, 
which will be the subject of his next paper. The present is limited to 
notices of certain new species of the Order, forming the types of three 
new genera. The first of these he describes under the name of Racheo- 
saurus gracilis: it is founded ona considerable portion of the vertebrae, 
ribs, pelvis, and hinder extremity of a skeleton, in the collection of 
Dr. Schnitzlein at Monheim, imbedded in a block of calcareous schist 
brought from Daiting near Solenhofen, the well-known locality o. 
Scemmering’s Crocodilus priscus and of so many other remarkable 
organic remains. The second, Plewrosaurus Goldfussii, Mey., is 
founded on nearly similar portions of a skeleton, also from the calcareous 
schist of Daiting, in the collection of Count Munster; it is described 
at much less length than the preceding specimen, and is not (as is the 
case with the Racheosaurus) figured either wholly or in detail. The third 
genus is established on a specimen in the Royal Museum at Dresden, 
