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The carapace is markedly hexagonal, flattened, but divided into a large anterior portion 

 and a much smaller posterior one by way of a prominent trans vers e crest, extending 

 nearly from side to side, most conspicuous across the cardiac region and gradually disappearing 

 laterally. On either side of this obtuse crest l ) the surface slopes forward or backward, bat is 

 rather uneven: the external branchial regions are, as usual, strongly declivous, and the whole 

 surface of the carapace shows a very short fur, which, if rubbed off, turns out to conceal a minute 

 oranulation. A short cervical groove, concave forward, separates the small gastric region from 

 the cardiac area; the latter itself is not defined posteriorly but passes into the somewhat bulging 

 intestinal region. The mesogastric region presents some lobules anteriorly, and laterally, on the 

 hepatic regions, there are on either side two obliquely-disposed verrucosities, forming a kind of 

 interrupted row from the mesogastric region towards the posterior lateral tooth of the carapace-, 

 similar, but rounded and longitudinally-arranged structures are found at either side of the 

 gastric region, and in the angle of the branchio-cardiac grooves. Hepatic regions depressed; 

 postfrontal lobes two in number, prominent, but not sharpened anteriorly, placed on the level 

 of the supra-orbital margin. 



The front is remarkably narrow, about one-third of the distance between 

 the orbital angles, obliquely-deflexed, with the margins thickened and granular; the antetior 

 border is divided into two lobules by the same longitudinal groove that separates the post- 

 frontal lobes; the lateral margins are concave, converging forward, and the anterior angles 

 are pronounced, acuminate. The supra-orbital border is perfectly transverse, save the 

 external third part, that is deeply excavate and rises towards the subrectangular outer orbital 

 tooth. The eye-stalks are comparatively long and slender, but somewhat shorter than the width 

 of the front, and the cornea does not reach to the outer orbital angle. The lateral margins 

 of the carapace are separable into two parts, the anterior ones being somewhat the shorter, 

 markedly d i v e r g i n g backward and divided into t h r e e obtuse t e e t h , i n c 1 u cl i n g 

 the external orbital angle, the anterior two teeth directed forward and 

 of nearly the same shape and size, the posterior tooth being shorter and 

 directed straightly outward; between the tips of these posterior teeth the carapace reaches 

 its maximum breadth and posteriorly the lateral margins are somewhat convex but rapidly 

 converging backward, so that the thickened posterior margin is distinctly shorter than the 

 distance between the outer orbital angles. 



The antennulae are folded obliquely beneath the front and separated by a triangular, 

 narrow plate (fig. 3 a) ; the antennae are placed in the orbital hiatus, as the inner suborbital 

 tooth does not join the front, the basal joint of the antenna is broad and quadrate, the two 

 following much narrower but of the same length, and the flagellum is rather long, outreaching 

 the eye-stalk. Suborbital border convex and minutely crenulate in its inner two-thirds, concave 

 and finely granular in its external part, that is very little . markecl ; pterygostomial regions 

 granular, with a longitudinal hairy groove; side walls of the body perpendicular and hairy. 

 Epistome short, but distinct ; anterior margin of buccal cavern with a strongly prominent ridge 



1) Stimpson speaks in his diagnosis of the genus of three or four interrupted transverse ridges on the carapace, but his draw ing 

 does not essen tially ditïer from the figure here given. 



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