NATURAL HISTORY — ZOOLOGY. 215 



angles to it the diacoeliacal diameter. Hereafter we must not take 

 the dictum of Mr. X. or Mr. Y., that "I hold this animal to be a 

 radiate ;" but we will submit it to the test, and if it does not stand 

 the test, we must throw it out. 



ANIMAL MONSTROSITY. 



Mr. G. Jeffreys has exhibited to the British Association several 

 specimens of the common whelk (Buccinum undatum) having double 

 opercula ; in one instance, a second or supplementary operculum 

 being piled on the usual one ; and in the others, there being two 

 separate opercula, instead of one, in each whelk. Mr. Jeffreys ad- 

 verted briefly to the different kinds of Monstrosity which occur in 

 animals and plants, and said he believed this to be the first case of a 

 similar monstrosity in the Mollusca. He observed that the monstrosity 

 under consideration appeared to be congenital, and not to have 

 arisen from an accidental loss of the original organ, because in some 

 of the specimens both opercula were cases of hypertrophy, and in 

 the others of atrophy ; and he mentioned that all the specimens 

 came from the same place (Sandgate, in Kent), showing a repetition, 

 and perhaps an hereditary transmission, of the same abnormal phe- 

 nomenon ; and he suggested that thus permanent varieties might in 

 course of time be formed, and constitute what some naturalists would 

 call "distinct species." He adduced, in support of this view, the 

 case of a reversed monstrosity of the common garden snail (Helix 

 aspersa), having been bred for many years in succession by the late 

 M. D'Orbigny, in his garden at Rochelle, as well as many instances 

 of a reversed form of almond whelk (Fusus antiquus) having occurred 

 in the same localities on the coasts of England and Portugal, such 

 being the normal form in the crag. 



Professor Henslow remarked that this was an important communi- 

 cation, as it tended to elucidate the very interesting and difficult 

 problem of the origin of species as treated by Mr. .Darwin. 



This, as well as the preceding paper, called forth remarks from 

 several speakers on Mr. Darwin's hypothesis of the production of 

 species by natural selection. 



SOCIETY FOR THE ACCLIMATIZATION OF ANIMALS. 



A Society for this purpose, upon a plan similar to that in Paris, 

 has been formed in London. Its objects are : — 1. The introduc- 

 tion, acclimatization, and domestication of all innoxious animals, 

 birds, fishes, insects, and vegetables, whether useful or ornamental. 

 2. The perfection, propagation, and hybridization of races newly in- 

 troduced or already domesticated. 3. The spread of indigenous 

 animals, &c, from parts of the United Kingdom where they are 

 already known, to other localities where they are not known. 

 4. The procuration, whether by purchase, gift, or exchange, of 

 animals, &c, from British and foreign countries. 5. The transmis- 

 sion of animals, &c, from England to her colonies and foreign parts, 

 in exchange for others sent thence to the Society. 6. The holding 

 of periodical meetings, and the publication of reports and transac- 



