272 Proceedings of the British Association, 



Mr. Busk referred to some drawings of sections of the cellular 

 structure of shells, in which some of the cells were perfectly black. 

 This was at one time supposed to arise from the presence of air, and 

 other causes ; hut he believed that it depended on the form of the 

 cell, which acted like a plano-convex lens ; the consequence was, that 

 the rays of light were so much refracted as to be lost. When a sec- 

 tion of this structure was looked at obliquely, the black spots entire- 

 ly disappeared. — Prof. E. Forbes remarked on the value of the mi- 

 croscope in every department of Natural History. With regard to 

 the tubes in the structure of the shell of Terebratulse, they were for- 

 merly supposed to be connected with the respiratory system ; but as 

 Dr. Carpenter had shown that that was not the case, he did not think 

 those tubes could be any longer regarded of generic value. 



* On the Sounds produced by one of the Notonectidse under Water,' 

 by Mr. Ball. — He stated, that the fact having been mentioned to 

 him some two years since, he had not had an opportunity of testing 

 the observation until within the last few days, when a specimen was 

 brought to him in an ordinary jelly glass ; it was, he believed, the 

 Corrixa affinis. When suspended in the water, about four inches 

 below the surface, it emitted three short chirrups, and then a long, 

 cricket-like sound. It appears, the sounds are emitted in the evening 

 and night, and are so loud that they may be heard in an adjoining 

 room, and are continued during the night. Mr. Ball stated, that time 

 did not permit him to make any accurate observation ; but he thought 

 the matter so curious, that he noticed it with the view of attracting 

 the attention of entomologists, in the hope of obtaining an explanation 

 of the manner in which this noise is produced under water. 



■ On the Scientific Principles on which Classification in the higher 

 Departments of Zoology should be based/ by Mr. Ogilby. — The 

 dental system was, no doubt, a valuable means of diagnosis, and this 

 depended upon the fact that it had a relation to the stomach, and 

 other viscera intended for the digestion of food. Just in the same 

 way, the extremities of the mammalia, more particularly the fore-arm, 

 are the exponents of the habits, mental power, and economy of ani- 

 mals. The fore-arm is the seat of the function of locomotion, of 

 manipulation and touch. According to the real position of an animal 

 in the scale of organization will be the character of its fore-arm. The 





