DECAPODA. 189 



RANINA, Lam., 



In which the elongated shell is gradually narrowed from before 



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



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



teini;r long and projecting. The external foot-jaws are similarly 



lengthened and riarro\v, 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 -. -ml 



towards the l>ack; the two last, however, are alone on it. The for- 



;ire r impressed, have the figure of a reversed triangle, and are 



denuued ; tin- fingers are suddenly flexed. 



Th'-M Cnist:i.-.-ji are closely allied to tin- Allmneae of Fabricius, 

 ihe fcrri Mih-uvniis of the t\)llowing 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 ;i> iu the Macroura. According to Rumphius, they not 

 only le:ive 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, Fab. 



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

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

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



* Rttninu Aldrorundi, Knnz., 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 strrata, Lam. ; Cancer raninus, L; Albunea scabra, 

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

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



The genus Sy met his, Fab., is unknown to us, but we presume it is allied to the 

 Rnminte, or the first subgcnera of the subsequent family. 



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

 > 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 -tnu-tmv to these natatory appendages. In the 

 first subtrencra 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 hare 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 thoe which we term the AnamaJu, the peduncle of the intermediate 

 antennae 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. 



