144 M. T. C. Winkler on 
Crustaceans must be ranged in the genus Glyphea, and belong 
to the species named G'. pseudoscyllarus, Schloth. Among 
these slabs of stone there are some which show only very 
mutilated and nearly undecipherable organic remains ; but in 
some of them the animal is preserved in a manner so perfect 
that it is not difficult to recognize the different parts of the 
body and to discern the characteristic marks of the species. 
This fortunate circumstance enables me to make a very com- 
plete description of this remarkable species of Glyphea; for 
the parts of the body which are deficient in one slab are fre- 
quently admirably preserved upon another. 
The cephalothorax is longer than broad; it is covered with 
tubercles which, on the anterior part, are arranged upon 
parallel lines, so as to form beaded salient lines, and behind 
the great transverse furrow are irregularly disseminated. 
Most of the specimens still present traces of depressions, ele- 
vations, and grooves which adorned the carapace during the 
life of the animal; but in general these characters have been 
more or less effaced during the fossilization of the body. 
However, the great deep transverse groove which, on each 
side of the cephalothorax, is directed towards the median line, 
and thus forms a semilunar line upon the carapace, separating 
the stomachal region from the posterior regions, is almost 
always met with. 
The segments of the abdomen appear smooth in most of 
the specimens; but in some they sometimes present isolated 
tubercles, and the most perfect specimen in our collection even 
bears some small tubercles on the seventh segment of the 
abdomen and on the lateral plates, which, with that segment, 
form a caudal fin of five lamelle arranged ina fan. This 
seventh segment is of a more or less triangular form, being 
not very wide and narrower behind than in front, while the 
lateral natatory lamelle are nearly circular. These ex- 
ternal lamelle are divided transversely ; and this. division 
leads one to suppose that these lamellze were soft and 
flexible for the posterior third of their length. ‘The first six 
segments of the abdomen present on each side a triangular 
lamellar process. It would appear that all these segments, 
or, at any rate, some of them, bore appendages in the form of 
small oval lamella, which, no doubt, were natatory false feet ; 
one of the specimens in the Teyler Museum presents one of 
these false feet isolated. The size of this appendage com- 
pared with that of the animal would lead one to suppose that 
this specimen was a female, as we know that in general the 
appendages of the abdominal segments are much more deve- 
loped in the females than in the males of existing Crustacea. 
