REPORT ON THE CRUSTACEA MACRURA. 83 



There can be little doubt, I think, that this specimen, which is a male about nine 

 inches in length, belongs to this species. It possesses the chief character given by 

 Milne-Edwards. " Anneau antennulaire arme de quatre dents eoniques fares grosses, 

 divergentes et reunies a leur base en faisceau." It also corresponds much in colour, for 

 although our specimen has been several years in spirits, it is still beautifully marked with 

 purple, blue, green, brown, and yellow, as in Lamark's description of Palinurus versi- 

 color, which Milne-Edwards considers to be identical, and the legs are marked with longi- 

 tudinal stripes. 



Though the geographical distribution of this species appears to be very extensive, 

 it seems to be chiefly limited to the southern and warmer seas. In the British Museum 

 there is a specimen supposed to be from the EedSea, but this perhaps may be Palinurus 

 ehrenbergi, Heller, to which it bears some resemblance. 



The branchial arrangement of this species corresponds more nearly with that of the 

 European form Palinurus vulgaris than with that of Palinostus (Palinurus) lalandii, a 

 circumstance showing that small branchial variation has generic value. 



The mastigobranchise are without the peculiar curve or notch that exists in those of 

 Palinostus [Palinurus) lalandii, except in the case of the third siagnopod, which is 

 longitudinally rigid and bent or notched at the extremity, folds backwards through its 

 whole length and enfolds the podobranchial plume, as may be seen in PI. XII. fig. 2. 



The arrang-ement of the branchiae is shown in the following; table : — 



Pleurobranchise, 

 Arthrobranchise, 

 Podobranchia;, 

 Mastigobranchia?, 



Observations. — It is in this species that the interesting transformation of the 

 ophthalmopod into an appendage resembling an antenna was observed by Prof. A. Milne- 

 Edwards and described by him. 1 He says, " guided by theoretical considerations, zoolo- 

 gists regard the movable eye-stalks, the appendages of the mouth, and the legs 

 of Crustacea, as being analogous organs {prganes analogues), resulting from secondary 

 modifications, impressed on different members of a series of appendages of the same order 

 which represent each other mutually in the organism as a whole ; but hitherto these 

 ideas were not supported by any fact which could be brought as evidence of the possibility 

 of the production of these various physiological instruments from one and the same 

 anatomical element. 



" One such teratologic^ case which I have observed in a Langoustes, Palinurus 

 penicillatus (Olivier), demonstrates the truthfulness of these ideas introduced into science 

 by Savigny, and developed by M. H. Milne-Edwards." 



1 Comptes renins, t. lis. p. 710. 



