ETYUS. 5 



Species unica. Etyus Martini, Mantell. Plate I, figs. 7 — 12. 



Etyus Maktini, Mantell. Med. of Great., p. 322, fig. 1. Geol. S.E. of Engl., p. 169, 



fig. 1. Morris, Cat., p. 58. 

 Reussia granosa, M'Coy. Ann. Nat. Hist., 1854. Contr. to Brit. Pal., p. 271, 

 fig. 4. 



Bescr. Carapace twice as broad as it is long, nearly plane from side to side, mode- 

 rately convex from front to back ; the anterior margin forming a perfect segment of a 

 circle, and armed with three or four tubercles ; the latero-posterior margin somewhat 

 hollowed ; the anterior portion of the carapace, including the gastric and hepatic regions 

 and the raetabranchial lobes, covered with small, sharp tubercles and granules of different 

 sizes ; the posterior portion simply granulated ; a larger distinct tubercle exists on each 

 mesogastric and one on each mesobranchial lobe. The nuchal furrow is almost 

 directly transverse, dividing the carapace into two nearly equal portions. The proto-, epi-, 

 and meso-gastric lobes are confused, and but slightly separated from the hepatic ; meta- 

 gastric lobe triangular, the anterior process extending forwards to the front ; the urogastric 

 rather large, without any tubercle, and but slightly distinguished from the cardiac region. 

 The epibranchial lobe very distinct, gibbous, strongly tuberculated ; the mesobranchial 

 somewhat pear-shaped, with a single, strong tubercle on the anterior part ; the meta- 

 branchial without tubercles ; the branchial sulci distinct. Orbits transverse, oval, open to 

 the antennary fossae, and separated only by a thin septum, where the front descends to 

 meet the narrow, triangular epistome ; the upper margin of the orbits has three tubercles, 

 which are excavated underneath in a very peculiar manner. Fragments of several of the 

 legs remain in one specimen in my possession, which show that they were long, slender, 

 and smooth. 



Length of carapace, 04 inch; breadth, OS inch. 



Found plentifully in the Gault, at Folkestone, in Kent ; at Ringmer, in Sussex ; and 

 rarely in the upper Greensand at Cambridge. Specimens exist in the British Museum, 

 in those of the Geological Survey and Cambridge, and in Dr. Bowerbank's, my own, and 

 other collections. 



Obs. The affinities of this species cannot be very satisfactorily determined by the 

 characters which are available in the imperfect specimens which have hitherto been 

 observed. There is, however, no ground whatever for considering it as an anoinurous 

 form, as suggested, with a query, by Prof. Morris, in his ' Catalogue.' It is undoubtedly 

 strictly brachyurous, and probably belongs to the great group of Canceridac, according to 

 the classification of our great carciuologist,* but its nearer affinities require an exami- 

 nation of many organs which do not exist in any known specimens to be accurately 

 determined. 



* EJw., 'Nat. Hist. Crust.,' vol. i. 



