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) but is at once distinguished from it by the armament of the 

 antero-lateral margins of the cai-apax. 



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 fi-out is narrower and more prominent 

 than in G. trideiis, 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, antennula?, antenna?, 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 3a), 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 \a). 



