S. I. Smith — Crustaceans of the Atlantic Coast. 
35 
G-eryon quinquedens, sp. nov. 
Plate IX, figures 1, la, lb, 2. 
This species is closely allied to G. tridens Kroyer (Plate IX, figures 
3, 3a) hut is at once distinguished from it by the armament of the 
antero-lateral margins of the carapax. 
In the larger specimens, the carapax, including the lateral spines, 
is about a third broader than long. The dorsal surface is considerably 
convex longitudinally, but only slightly transversely, entirely naked, 
finely, but irregularly, granulated, and not deeply areolated. The 
most prominent elevation is a short, rounded, transverse ridge each 
side, between the base of the lateral spine and the posterior portion 
of the gastric region. The front is narrower and more prominent 
than in G. tridens , its breadth between the tips of the inner angles 
of the orbits only equaling the width of the orbit itself between the 
tips of its inner and outer angles. The median teeth of the front are 
near together, triangular, and deflexed below the level of the inner 
angles of the orbits, in front of which they project for almost or quite 
their whole length. The outer angles of the orbits are acutely angu- 
lar, but broader and less spiniform than in G. tridens. The next 
tooth (the second of the five normal teeth of the antero-lateral mar- 
gin), which is entirely wanting in G. tridens, is a well-developed 
angular projection of the margin, but less prominent than the first 
tooth and not acutely angular. The third tooth is prominent, acutely 
triangular, but scarcely spiniform, and much shorter than in G. tridens. 
The fourth tooth, which, like the second, is entirely wanting in G. 
tridens, is represented by a distinct but only slightly angular emar- 
gination which is more conspicuous in the smaller than in the larger 
specimens. The postero-lateral margins are nearly straight as in G. 
tridens. In young specimens the three larger teeth of the antero- 
lateral margin are more acute and spiniform than in the larger 
specimens examined. 
The eyes, antennuhe, antennae, and epistome are very nearly as in 
G. tridens, but the inner angle of the inferior margin of the orbit is 
much less prominent in the new species. In G. tridens, this angle 
projects as a slender tooth to the extremity of the peduncle of the 
antenna, reaches as far as the outer angle of the orbit and nearly as 
far as the front itself (Plate IX, figure 3 a), while in our species it is 
much less slender, falls far short of either of the other angles of the 
orbit and reaches but slightly beyond the third segment of the 
antenna (figure la). 
