24 CRUSTACEA. 



are almost insensibly connected. They may all be united in one 

 single subgenus, that of 



PoRTUNUs, Fab. 



Certain species(l) peculiar to the Indian Ocean, such as the Ad- 

 mete, Herbst., LVII, 1, are distinguished from all the following 

 ones by their shell, which is of a transversely quadrilateral form, 

 narrowed posteriorly, and whose ocular cavities occupy its anterior 

 lateral angles; the eyes are thus separated by an interval almost 

 equal to the greatest width of the shell. The insertion of the lateral 

 antennas is at a considerable distance from these cavities. 



Other species, whose shell forms the segment of a circle, poste- 

 riorly truncated and widest in the middle, are remarkable for the 

 length of their claws, which is at least double that of the shell. 

 Each side presents nine teeth, the posterior largest and spiniform. 

 The tail of the males is frequently very different from that of the 

 females. 



These Portuni constitute the genus Lupa, Leach, and are mostly 

 of a large size and foreign to Europe. One species, however, is 

 found in the Mediterranean(2). 



A third division will consist of species analogous to the last in 

 the form of their shell, but whose lateral teeth, usually five in num- 

 ber, are nearly equal, or where, at least, the posterior tooth differs 

 but slightly from the preceding onesj the length of the claws does 

 not much exceed that of the shell. 



Those which have from six to nine teeth on each side are 

 exotic. The Portunus tranquebaricus, Fabr., Herbst, Cane, 

 XXXVIII, 3, is the only one known that has nine equal teeth 

 on each lateral edge; it is large, and is much esteemed as food. 

 We suspect the P. leiicodonte, Desmar., Hist. Nat. des Crust. 

 Foss., VI, 1 — 3, is the same species in a fossil state; it is also 

 from India. 

 The following species, all from European seas(3), have five teeth 

 on each lateral edge of the shell. 



(1) Genus THAtAMiTA, Lat. 



(2) Portunus Dufourii, Latr., Nouv. Diet. d'Hist. Nat., Ed. II. This species, 

 figured in the Diet. Class. d'Hist. Nat., closely approaches the Cancer hustatus, 

 Lin., which he says is found in the Adriatic. The following are to be referred to 

 the same division: Cancer pelagicus, Herbst., Iviii, 55, — C. forceps. Id., Iv, 4; 

 Leach, Zool. Miscell., liv; — C. sanguinokntus, Herbst., VIII, 56, 57; — C. cedonulU, 

 Id., xxxix; — C. reticulatus, lb., 1; — Chastatus, lb., Iv, 1; — C. menestho, lb., 3; — 

 C. ponticus, lb. 5. 



(3) For the Mediterranean species see Petagna, Rissoand Ollvi; for those on the 

 western coast of France and the British seas, the Catalogue Methodiquc des Cms- 



