270 CRETACEOUS CRUSTACEA. 



is a very elongate pear-shaped one, having one side coincident 

 with the nuchal furrow, and a long transverse elongated ele- 

 vation, extending behind the tapering inner end of the last, 

 angulated in the middle beyond the termination of that lobe, 

 and thence bent abruptly backwards and inwards behind the 

 posterior gastric lobes to the uro-gastric lohe, which cannot 

 be distinctly separated from the cardiac lobe, but is flanked 

 on each side by the deep lunate hollows, or little fossse pro- 

 duced by the attachment of the posterior gastric muscles ; 

 posterior cardiac or intestinal region not distinctly defined 

 from the branchial regions, which latter have a small curved 

 elevated elongation, bordering the inner anterior angle. All 

 these contorted lobe-like elevations on the anterior half of the 

 carapace are very minutely granular, edged by a single row of 

 slightly larger granules, and separated by broad, deep, smooth, 

 concave furrows; the posterior half of the carapace is uni- 

 formly minutely granular. Average length 1 inch 2 lines, 

 proportional greatest width y^^ (often larger). 



This very beautiful and distinct species is larger and flatter 

 than the others of the genus, and destitute of the tubercles with 

 which their carapace is marked, by which character, as well as 

 the very curious, slightly elevated, map-like, contorted, lobular 

 markings of the anterior half of the carapace, it is easily distin- 

 guished from its congeners. It is comparatively rare, scarcely a 

 dozen specimens having been found, while nearly a hundred 

 have been found of the N. Mantelli (M'Coy). 



Upper greensand of Cambridge. 



[Coll. Mr. Carter, Cambridge.) 



Reussia (M'Coy), n. g. 



Gen. Char. Small : carapace moderately tumid ; transversely 

 elliptical, front very strongly rounded ; anterior lateral mar- 

 gins obtuse ; orbits of moderate size, broad-oval, approximate : 

 most of the regions of the carapace sharply defined by narrow 

 sulci; meso-gastric lobe triangular behind, abruptly narrowed 

 to a linear tongue-shaped extension in front, reaching to the 

 point of the obtusely angular rostrum, where its apex is 

 flanked by two small oval swellings, indicating the anterior 

 gastric lobes-, proto-gastric lobes large, slightly defined on 

 their outer margin; posterior gastric lobes united into one 

 transversely oblong space, slightly wider than the base of the 

 meso-gastric lobe, flanked at its posterior corners by the two 

 lunate fossse of the posterior gastric muscles ; uro-gastric and 

 cardiac regions undefined, tumid ; posterior branchial regions 

 much depressed; anterior branchial or epibranchial lobe or 



