1 38 Zoological Society. 



instances, that the variation of the species, in each of these sub- 

 genera, is regulated on precisely the same principle. Hence it fol- 

 lows that the two circles of Mitra and Tiara, like the two divisions 

 of Mr. MacLeay's Petalocera, contain species representing each 

 other, so that if their generic character is not attended to, it is 

 almost impossible to discriminate them even as species. Many in- 

 stances of this extraordinary analogy might be mentioned, indepen- 

 dent of that here alluded to, between Mitra Terehralis and Tiara 

 Terebrans. 



" Selecting this shell to illustrate the numbers "Type 4,4," I 

 may observe, that ' Type 4 ' signifies that it belongs to the fourth 

 subgenus of Tiara, in which group it is the fourth subtype, uniting 

 to Mitra maura, which is the fourth subtype of the first or typical 

 subgenus. Mitra maura, again, as representing this latter shell, 

 consequently becomes the fourth subtjqie of the first or typical sub- 

 genus, and is therefore marked " Type 1, 4." The first figure always 

 denotes the subgenus, and the last the station which the species ap- 

 pears to hold in its own subgenus. 



" I am unacquainted with any group in the animal kingdom 

 which demonstrates more fully than this does the law of represen- 

 tation. It may be mentioned, also, that nearly all the divisions I 

 had long ago characterized, from the formation of the shells alone, 

 have more recently been confirmed by a knowledge of their respec- 

 tive animals : a knowledge for which we are entirely indebted to 

 the able naturahsts who accompanied the French expedition on 

 board the Astrolabe." — W. S. 



Specimens were exhibited of several hitherto undescribed Cowries, 

 most of which have been brought to England within the last few 

 years. They were accompanied by characters and descriptions by 

 J. S. Gaskoin, Esq., which are given in the " Proceedings" under 

 the following names, viz. 



Cypraa formosa (Cape of Good Hope), rubinicolor, prodticta, candi- 

 dula (Mexico, Cyp. approximans , Beck, Cyp. olorina Duclos, but first 

 described by Mr. Gaskoin), acutidentata (Isle of Muerte, Bay of 

 Guayaquil), Pediculus, var. labiosa, vesicularis (Cape of Good Hope), 

 and Beckii. 



There was read an "Extrait du Quatrierae Rapport Annuel sur 

 les Travaux de la Societe d'Histoire Naturelle de I'lle Maurice : par 

 M. Julien Desjardins." 



The communications relative to the Mammalia read before the Na- 

 tural History Society of the Mauritius in the fourth year of its ex- 

 istence have comprised an account by the secretary, M. Julien 

 Desjardins, of a Wliale which he regards as the Physeter macroce- 

 phalus, Linn., that was cast ashore on an adjoining reef: and some 

 observations by the same author on several of the Maminalia of the 

 island, and particularly on the hybernation of the Tenrec, Centenes 

 spinosus. 111. ; the lethargy of which animal takes place when the 

 thermometer is not lower than 20° Cent., and even when it marks 26°. 

 In ornithology M. Desjardins has also been the only contributor. 

 He has described, as new, two Birds belonging to the island, and has 



