189 



Ranina, Lc 



In which the elongated shell is gradually narrowed from before 

 backwards, and usually resembles a reversed triangle with a den- 

 tated base. The ocular pedicles are extended, and the lateral an- 

 tennae long and projecting. The external foot-jaws are similarly 

 lengthened and narrow, and the extremity of the third joint is com- 

 pressed into a point. All the feet are closely approximated, or 

 almost contiguous at their origin, and from the fourth pair ascend 

 towards the back ; the two last, however, are alone on it. The for- 

 ceps are compressed, have the figure of a reversed triangle, and are 

 dentated ; the fingers are suddenly flexed. 



These Crustacea are closely allied to the Albuneee of Fabricius, 

 the first sub-geiuis of the following family, and thus form the passage 

 from the Brachyura to the Macroura. From the approximation of 

 the feet it is even probable that the genital orifices of the female are 

 situated as in the Macroura. According to Rumphius, they not 

 only leave the water, but even climb to the tops of houses ; from the 

 form of their feet, however, this appears impossible, or at least very 

 improbable. 



A fossil species was described by Aldrovandus, which the 

 Abbe Ranzani and M. Desmarest have since made better 

 known *. 



FAMILY II. 



MACROURA.— ExocHNATA, Fah. 

 In the Decapoda Macroura, the end of the tail is provided witli 

 appendages! which most frequently form a fin on each side ; the tail 

 itself is at least as long as the body, extended, exposed and simply 



* Ranina Aldrovundi, Ranz., Mem. di Stor. Nat. ; Desmar., Hist. Nat. des 

 Crust. Foss., VI, xi, 1. The fig. x, 5, 6, appears to us to belong to a Hippa 

 rather than to a Ranina ; — Ranina serrafa, Lam. ; Cancer raninus, L; Alhunea scabra, 

 Fab.; Rumph., Miis., VIT, T. V. ; — Ranina dorsipes, Lam.; Albunea dorsipes, Fab.; 

 Rumph., Mus., X, 3; Desmar., Consider., XIX, 2. 



The genus Si/inethis, Fab., is unknown to us, but we presume it is allied to the 

 Raminse, or the first subgenera of the subsequent family. 



f These appendages consist of three pieces, one of which serves as a base or 

 pedicle to the others, and is articulated with the penultimate segment ; the latter, 

 in conjunction with them, usually forms a fan-like fin; but in the last subgenera of 

 this family these appendages are replaced by setaceous filaments. The false feet 

 under the tail are similar in their structure to these natatory appendages. In the 

 first subgenera they frequently do not exceed three or four pairs, and are smaller, 

 or even null in the males, the two anterior ones always excepted ; the Pagura, as 

 it appears to me, only have them on one side: the terminal pieces are often un- 

 equal. In the succeeding ones, however, these feet are longer, and always form 

 five pairs, the ova attached to them ; and they are used by the animal in swimming. 

 We observe that in the Macroura, where they are fewer in number, or less de- 

 veloped as in those which we term the Anomala, tlie peduncle of the intermediate 

 antennee is longer in proportion than in the others, and that the two or four last 

 four feet are smaller. These Crustacea, in some respects, seem also allied to the 

 Brachyura. 



