18 FOSSIL MALACOSTRACOUS CRUSTACEA. 



deep and quite smooth; epigastric lobes small, and scarcely distinct from the 

 protogastric, which are large, and separated by the long, narrow process of the 

 nasogastric ; this is of a general pentagonal form, and is divided from the metagastric 

 by an arched furrow ; the urogastric lobe is not distinguishable from the metagastric ; 

 cardiac region pentagonal ; hepatic region with a rounded elevation, the hepatico- 

 branchial furrow very broad and distinct ; branchial region large, the gastro-branchial 

 furrow very deep at the junction of the gastric and cardiac regions ; the epibranchial 

 lobe elevated, with a distinct lobule adjoining the urogastric; mesobranchial very 

 small and distinct ; metabranchial obliquely truncated at its outer margin ; orbits 

 of moderate size, directed outwards, the hiatus filled jointly by the basal articulation 

 of the external and the outer edge of that of the internal antenna?, the latter large 

 and triangular, the former small and quadrate ; epistome with a triangular process joining 

 the front, and thus, as usual, separating the two antennary fossae ; external footjaws 

 with the inner stalk elongate, straight, and narrow. As all the specimens which have 

 come under my observation were much broken at this part, I have been unable to 

 ascertain any further particulars of the structure of these important organs. Anterior legs 

 very large, unequal ; the wrist and hand partially granulated ; the fingers of moderate 

 strength, slightly grooved longitudinally, and with scarcely any tubercles on the opposing 

 edges ; they have strikingly the appearance of having been of a different colour from the 

 rest of the body, a peculiarity which obtains in the recent genus Xantho, and which 

 affords an interesting collateral indication of the relation of the two genera. The 

 ambulatory feet rounded, and without any armature. Abdomen in the female elliptical, 

 with a longitudinal furrow on each side ; all the segments separate. All the specimens 

 which I have seen being females, I can give no account of the male abdomen. 

 Length of the carapace, 1"5 inch; breadth, 1*8 inch. 



Obs. The most obvious relation of this genus is to Xantho ,-* and its affinities to this 

 genus are much more considerable than are those of Xantliojjsis. It differs, however, 

 from that form in some particulars, which appear quite sufficient to justify its generic 

 distinction. The carapace is much longer in proportion to its breadth, and although 

 equally flat from side to side, the anterior part is much more curved downwards ; the 

 external footjaws are proportionally much narrower, and the hiatus of the orbits, instead 

 of being closed exclusively by the basal joint of the external antennae, are partially closed 

 also by that of the internal. 



The specimens are numerous in the collections of Mr. Bowerbank and Mr. Wetherell, 

 and there are a few in the British Museum. These are, I believe, exclusively, from the 

 Isle of Sheppey ; and I have seen some mutilated and worn specimens from Southend, in 

 the collection of Mr. Prestwich. 



* The species of Xantho to which it is most nearly allied appears to me to be X. affinis of De Haan, 

 ' Faun. Japon. Crust..' t. xiii, fig. 8. 



