Pemphix, Glyphea, and Areeosternus. 135 
genus G'lyphea. By means of the description of Arwosternus 
Wieneckei and the diagnoses and descriptions of the species of 
fossil Glyphece which occur in the different paleontological 
works, I hope to be able to prove what [ advance. But, 
what is more, my investigations have proved to me that the 
genus Areosternus, De Man, is very probably the existing 
representative of a very long series of extinct genera—that we 
may follow the traces of its ancestors through the Tertiary, 
‘Cretaceous, and Jurassic periods back to the epoch of the 
Lower Lias—that there is a series, an uninterrupted succession, 
which commences with a liassic genus, and terminates in the 
recent genus—that probably the ancestry of these successive 
genera, which commence with the liassic Glyphee, must be 
sought in a geological period anterior to that of the Lias, in 
the Triassic period, and that this origin of the long series of 
the Glyphee is to be found in the species described under the 
name ot Pemphix (Palinurus) Sueurt. 
In order to demonstrate that my hypothesis is well founded, 
dt is necessary, in the first place, to glance at the genus Pem- 
phix, then to give a short historical sketch of the genus 
Glyphea, adding thereto a description of the specimens of that 
genus contained in the Musée Teyler. After this statement I 
shall make known the specific characters of Araosternus 
Wienecket, De Man. I shall demonstrate that perhaps the 
Glyphee descend from the genus Pemphix; then I shall com- 
pare Arwosternus with the genus Glyphea, pointing out the 
analogies which unite and the differences which separate 
these two genera; and, finally, I shall discuss the arguments 
and considerations which lead me to see in Arosternus 
Wienecket, De Man, the last representative of a series of lost 
forms, the last existing genus of a succession which is probably 
in course of becoming extinct. 
Il. Glance at Pemphix Sueuri, von Meyer. 
In 1822 Desmarest gave a description of the carapace of a 
Macrurous Decapod Crustacean under the name of ‘ Langouste 
de Lesueur” (Palinurus Sueurt). He says that this carapace, 
which is petrified in calcareous material, is nearly of the size 
of that of a common crayfish and granular all over; it has a 
very small triangular rostrum hollowed into a groove, and no 
spines in front; the rest of the anterior margin is too imper- 
fect to be described. Its surface is divided into three distinct 
parts by transverse impressed lines, the first of which is not 
very sinuous, and the second wider, V-shaped and_ bordered. 
The first two parts separated by these lines are tuberculous; one 
of them, the anterior, is the stomachal region, and the second 
