P0RTUN1TES. 21 



Species unica. Portunites incerta, mihi. Plate III, figs. 1 — 5. 



Descr. Carapace broader than it is long, in the proportion of three to two, much 

 flattened in the adult state, more elevated when young ; the surface granulated ; the 

 regions distinct, the separating furrows rather broad and generally free from granulations ; 

 gastric region with the lobes very distinct ; epigastric small and inconspicuous ; 

 protogastric considerably raised, rounded, and separated from each other by a narrow 

 process of the mesogastric which extends forwards nearly to the front ; nasogastric 

 and metagastric lobes continuous with each other, and forming together an elongated 

 pentagon ; urogastric short, separated from the former by a slight depression ; cardiac 

 region with a broad but low elevation on the anterior lobe ; hepatic regions rather large, 

 with a slight transverse elevation ; branchial regions with the epibranchial lobe curved, 

 narrow, and somewhat raised, extending from the metagastric to the lateral margin; 

 the metabranchial portion traversed by a straight longitudinal ridge, against the outer 

 side of which the fifth leg rests when turned over the back; a smooth depression 

 just within the posterior margin, front entire ; latero-anterior margin with the normal 

 number of teeth (five), of which the fifth is the longest, triangular and pointed ; orbits 

 oval, extending outwards as far as the middle of the hepatic region, with two fissures 

 above, and apparently none beneath ; epistome rhomboidal ; external footjaws longitudinally 

 furrowed ; anterior legs short and robust ; the arm smooth, the wrist with a strong 

 tubercle on the inner anterior angle, the hand slightly rugose, the outer margin slightly 

 bicarinated, and with another inconspicuous carina on the upper side ; fingers strong, 

 longitudinally grooved, with tubercles on the opposed edges ; the remaining legs slender, 

 smooth, the terminal joint lost in all the specimens observed ; male abdomen hastate, 

 with the third, fourth, and fifth joints united ; the female abdomen oval, with the whole 

 of the joints separated. 



Length of carapace, 1*2 inch ; breadth, 0*9 inch. 



05s. I have ventured to consider as nearly allied to Portunus a species, a considerable 

 number of specimens of which are in the British Museum, and in the collections of 

 Mr. Bowerbank and Mr. Wetherell, and in my own, all of which I believe are from 

 the Isle of Sheppey. They are too much mutilated or otherwise imperfect to enable 

 me with any absolute certainty to pronounce upon its generic relations, but the resem- 

 blance to Portunus is sufficiently obvious to warrant its location in the same family, and 

 in no very remote situation from the typical forms. The absence of the terminal joint of 

 the fifth pair of legs in all the specimens observed, prevents our ascertaining how far the 

 natatorial habits indicated by the general organization would be borne out by the 

 structure of that essential element. The whole of the posterior pairs of legs, as far as 



