PROCEEDINGS OF SOCIETIES. 145 



equal to the specimens first sent. As far as he had been able to judge, 

 they were still of the first class. He felt personally indebted to Mr. 

 Curties for his kindness in allowing him time for a fair judgment, 

 and thought the members, as microscopists, were under an obligation 

 to him for the opportunity he had afforded them. 



Mr. Sewell, who had a ^rd out of the first batch, was well satisfied 

 with its performance, and could not wish for a better lens. 



Mr. Wonfor expressed himself as well pleased with what he had 

 already seen, and doubted not the members would be delighted with 

 these lenses, not only as regarded their performance, but also their 

 cheapness. He would suggest that the objects to be shown that even- 

 ing should be seen with Gimdlach's lenses, and a comparison be made 

 with other objectives by the members present. Upon all occasions 

 Mr. Curties had acted in a most courteous and kindly way to the 

 Society, and he should have great pleasure in proposing a cordial 

 vote of thanks to him for this and other acts of kindness. 



Mr. Sewell seconded the resolution, which was carried unanimously. 



Mr. Wonfor then introduced the subject for the evening, " Shell 

 Structure," by describing the structure and component parts of the shells 

 among the Mollusca, at one time supposed to be mere inorganic exu- 

 dations, cemented together by animal glue. It was now known that 

 theii' shells were composed of animal and calcareous matter, the first 

 constituting a membranaceous basis, forming cells, with hexagonal 

 walls or laminae, more or less wrinkled ; some shells were traversed 

 by tubes, others by canals, with trumpet-shaped orifices ; in each case 

 the calcareous matter giving solidity to the membranaceous tissue. 

 The internal layer, of a nacreous nature, was in many very beautiful. 

 Some of the porcellaneous shells were made up of three distinct layers 

 of a similar structure. In the Crustacea, especially the crab, four 

 layers could be distinctly made out, one of which strongly resembled 

 dentine, except that the tuhuli did not branch, but remained of the 

 same size throughout. It was in the cellular layer where the pig- 

 mentary matter, which imparted the colour to the shell, was to be 

 found. The membranaceous matter could best be made out by decal- 

 cifying the shell and cutting thin sections. 



The meeting then became a conversazione, when Mr. Hennah ex- 

 hibited, under Gundlach's yVth and ^s^^^ sections of crab and cowrie- 

 shell, mounted with thick covers. The performance was perfect. 

 Afterwards, for lined objects, Pleurosigma angulatum and tasselled 

 scales of white butterfly were shown. The y\rth gave very good 

 results ; but the xV*^ ^^^ ^o* equal Beck's popular ith. 



Mr. Sewell exhibited with a ^rd, sections of pearl and crab-shell. 

 This lens was pronounced very good, 



Mr, Peto, imder a i and a 1 inch, with convex front, exhibited 

 sections of pinna-shell. Both lenses were excellent. 



Mr, Wonfor, under a couple of ^rds, exhibited egg-shell of garden 

 snail, sections of shell of terebratida, shells of prawn, shrimps, &c. 

 These lenses were very good, and when compared with Mr, Sewell's 

 J^rd to test equality of performance, were so nii;ch alike that scarcely 

 a difference, if any, could be detected. 



