90 



separate the Laguna del Potrero from the shores of the Plata, at 

 the distance of a few miles from Maldonado." The exhibitor con- 

 sidered that a particular interest attached to his specimens because 

 they had been obtained from the small area of pand described by 

 Darwin more than eight}' years earlier. At that date fulgurites 

 were little known — they can scarcely be said to be well-known at 

 the present time — and Darwin refers to some that had been found 

 at Drigg, in Cumberland, which had been described in vol. ii. of 

 the Geological Transactions. In recent years they have been found 

 also in a district in Poland, but they do not appear to have become 

 common objects anywhere. This fact probably indicates that 

 special qualities of sand or local conditions favour the fusibility of 

 the grains. It is believed that the tubes are cylindrical when 

 formed, but that their shape is altered by local pressure before 

 cooling takes place. 



Mr. J. Piatt Barrett exhibited series of Thais ]>olyxena, Lencnchloe 

 [Pontia) daplulice, Eiichloe {Anthocharis) belia {craiiieri] and Antho- 

 charis [Enchlo'e) cardamines and contributed the following notes : — 



" I am showing four species of butterflies, which may be termed 

 "variable," in fact with them " vatiation is the rule" and not 

 the exception, and after careful examination it would be probably 

 correct to say that no two specimens are exactly alike. A small 

 dot may be enlarged, a blotch altered in shape, colouring slightly 

 altered and so on; yet on the whole there remains a wonderful 

 uniformity in the 65 specimens comprising this exhibit. 



(1) Thais polyxena is a very striking species and should show at 

 least one of the abnormal forms, var. runtina, with extra red spots, 

 var. Cassandra blacker, ab. ochracea dark instead of light yellow, 

 ab. meta red spots replaced by yellow, or ab. bella the third costal 

 spot reduced in size, but only one of my specimens differs a little 

 and may approach ab. ochracea. I have only met with L. polyxena 

 on one slope in Sicily, and this may account for getting no varieties. 



(2) Leucocklo'e [Pontia) daplidice. — A new genus has recently 

 been created for daplidice and another species, and is differentiated 

 from the ordinary "whites" [Pieris) by the sub-costal vein, which 

 has three branches (Pj>>7s has four and Anthocharis i\ve). Certainly 

 daplidice seems to agree more closely to Knchlo'e [Anthocharis) belia 

 [crameri) than to Pieris or to Anthocharis, and it would not do much 

 harm if the Leucochloes and the Euchloes were combined in one 

 genus. L. (P.) daplidice is very common both in Sicily and in 

 Calabria and two so-called abnormal forms are shown, (1) var. 

 bellidice the spring form, which is smaller and darker green, and 



