■Extracts from the Minute-Book of the Linnean Society. 585 



proving that these insects, which have been hitherto 

 considered as distinct species, are the sexes of the 

 same, P. Folycaon being the male. This interesting 

 specimen is from Brazil, and was sent to Mr. Mac- 

 Leay by John Dixon, Esq., of Rio de Janeiro. 



l^ov. 2. Mr. James De Carle Sowerby, F.L.S., presented 

 specimens of a Fresh-water Shell, probably the Myti- 

 lus polymorphus, Gmel. 3363, which is found in abun- 

 dance, attached to shells and timber, in the Commercial 

 Docks by James Bryant, Esq., who uses the animal 

 as bait for perch. Mr. Sowerby observes, that " the 

 strong resemblance which it bears to the marine My till 

 is very remarkable. Independently, however, of the 

 septa within the valves, there are many other diffe- 

 rences to be observed, several of which are in the 

 structure of the included animal, although it possesses 

 a strong byssns: among others, the foot is small, and 

 the lips of the mouth are differently placed, being more 

 like those in the animal of the Unio ovalis. It has two 

 tubes, and the mantle is united almost all round, and 

 bordered with a band of bright orange between two 

 bands of black. Some of the septa within the beaks 

 appear to be a kind of disease, as they are not con- 

 stant. The same species is found in the Danube, and 

 in the rivers of Russia; but the British specimens 

 are much larger and finer than any foreign ones I have 

 seen." 



l<lov. 16. Read a Letter from Mr. John Atkinson of Leeds, 

 F.L.S., accompanied with some specimens of Cole- 

 opterous Insects which were discovered among the 



linen 



