Pemphix, Glyphea, and Arzosternus. 307 
representatives of that genus which exist in the Musée Tey- 
ler, we have studied the organization of Arw@osternus Wie- 
necket, De Man, according to the description published by the 
learned carcinologist of Leyden; and now let us examine 
into the differences which separate and the resemblances 
which unite the genus Pemphix and the G'lyphee, in order to 
learn whether it is permissible to regard the genus Pemphix 
as the direct ancestor, the original of the genus Glyphea. 
Let us first see what are the differences. 
The cephalothorax in Pemphix is distinguished from that 
of the Glyphee by the principal grooves which divide it into 
three distinct parts, and by the form of the regions which are 
_surrounded by these furrows. ‘The cephalothorax of the 
Glyphee is divided into. two principal parts by a single 
groove, the nuchal or transverse groove. In general the sur- 
face of the cephalothorax in Pemphix is more ornate than that 
of the Glypheew, the tubercles are more robust, the different 
regions are characterized by convex forms, depressions, &c. 
The front is more pointed, and the lateral incisions or sinuses 
of the anterior margin of the carapace are deeper than in the 
genus Glyphea. . 
There is one interesting question, namely to know whether 
the ambulatory legs of Pemphix differ or not from those of the 
Glyphee. We know that von Meyer (‘ Neue Gattungen 
fossiler Krebse,’ p. 6), in speaking of the anterior limbs, says, 
“The anterior limb is stouter and longer than the others ; it 
would hardly seem that it was armed with a pincer, such as 
has been ascribed to it. One would rather think that its last 
jomt was a slightly curved claw, and that the penultimate 
joint had no finger-like process. Pictet (‘Traité de Pal. i. 
p- 444) says that the anterior limbs are not well known.” 
Quenstedt places Pemphix Sueuri among the Locustine, 7. e. 
among those Macrurous Crustacea of which the first pair of 
limbs possess no chele. This author, in speaking of the 
description given by Hermann von Meyer, says (Handb. der 
Petretact. p. 824), ‘‘ According to him the anterior limbs are 
stronger than the rest, and terminated in a pincer.” Here 
the author places a? He proceeds, ‘‘ Although in examining 
the figure one is not convinced of it, it is nevertheless certain 
that the succeeding legs bear pincers. In the Muschelkalk of 
Wiesen, in Switzerland, I have found a specimen in which 
the terminal joint of the first pair was perfectly preserved ; it 
only terminates in a claw, as in the Locuste.” 
It is therefore doubtful if we are to regard the feet of the 
first pair in Pemphiz as a difference distinguishing that Crus- 
tacean from the Glyphee, or whether we are justified in finding 
