90 The Scottish Naturalist. 



As these various meetings of learned Societies have been fully reported in 

 scientific journals, we need not recapitulate these well-executed reports. 



Mr. James Stewart, L.D.S., followed with a paper on the Comparative 

 Anatomy of the Teeth, in which, after vindicating the importance and 

 value of the study of comparative Anatomy, he gave an account of the teeth 

 and of the leading modifications undergone by them in the great classes of 

 Fishes, Amphibia, and Reptiles. 



January 8. — Mr. Stewart continued his lecture on Teeth, dwelling on the 

 characters and modifications of these organs in the Mammalia. 



Dr. Trotter contributed a paper on The Diatoms of the Tay, based on 

 personal observations, and dealing more especially with those of the neighbour- 

 hood of Perth. Around the city are sandy ridges, which in many places rest 

 upon an extensive bed of brick clay. In many places the spicules of sponges 

 abound in this layer. Here and there are deposits of blue clay that had 

 formed in hollows of the brick clay ; and these yield many diatoms, almost ex- 

 clusively of marine or brackish-water types. Perth stands on deposits of these 

 different clays. 



January 22. — A largely-attended conversazione was held in the Museum 

 buildings, and the newly-arranged cases were the object of much attention, 

 particularly those containing the birds of Perthshire along with their nests and 

 eggs. Several microscopes were in use during the evening. 



February 7. — Mr H. Coates exhibited a snail-slug ( Testacella haliotidea 

 Drap. var. scutulum), which had been sent to him from near Kirkcaldy by Mr. 

 W. D. Sang. The species has not previously been found in Britain north of 

 Durham. It seems thoroughly established (probably naturalised) near Kirk- 

 caldy, though seldom seen, except early on wet mornings in spring and autumn. 

 He also exhibited a shell of Helix nemoralis, found at Invergowrie, of which 

 the last whorl had been quite displaced so as to resemble one shell growing 

 within another (but the inside was so repaired as to be smooth) ; and a shell oi 

 Planorbis vortex, from Errol, in which the last whorl is bent abruptly to one 

 side, and is quite detached from the previous whorl. 



Mr. Coates afterwards read a paper on Shells ; their Structure, Growth, 

 and Uses, in which he discussed the nature of shells, and defined them as 

 hard external coverings peculiar to the mollusca, serving at once as a "dwelling 

 place and a citadel." The connection of the shell with the animal, its mode 

 of formation and growth, and the uses to which it may be put, were more or 

 less fully dealt with. 



At each meeting several members were added to the Society, and numerous 

 donations to the Society's very excellent local museum were announced. 

 Among these a number of Perthshire mammals were a response to the appeal 

 for aid made by the President (Dr. Buchanan White) in a preceding meeting. 



