Gould.] 78 



senses. He considered that a correct and Tiniform use was 

 possible, since the consideration of the animal had come to be 

 combined with that of the shell by refening the terms to the 

 related position of the animal. 



Taking a common clam for an example, and placing it with the 

 beak uppermost, lie showed the position of the enclosed organs, and 

 that the extremity which was in front during locomotion should be 

 called the anterior^ and the opposite, the posterior extremity ; that 

 the distance from the beak to the opposite margin should be called 

 the altitude, the distance from the anterior to the posterior extremity, 

 the longitudinal diameter, and the distance through from one valve to 

 the opposite the transverse diameter; that the concentric markings 

 of growth should be called longitudinal, in distinction from those 

 which radiated from the beak to which the name of vertical should 

 ^be applied. The terms equilateral, posterior side and anterior side, as 

 used, he showed to be peculiarly improj)er, and suggested Instead the 

 terms equipartite, posterior part, segment or section, etc. Passing then 

 to the common spiral shells through the medium of LImax, Patella, 

 DentaUum, and Vermetus, he showed that the radiating or spiral strise 

 in like manner should be denominated vertical, and those which 

 crossed the single whorls or the concentric lines of growth longi- 

 tudinal stride — that in reality the longitudinal diameter of a shell 

 was the width of the largest whorl at Its aperture, and Its altitude the 

 length of the unrolled spiral, and thus the terms used In the descrip- 

 tion of ail shells become identical for analogous parts. For conven- 

 ience however, we may speak of the altitude of the spire as distinct 

 from that of the shell, and so of its length ; the anterior extremity and 

 other relative terms were to be determined In this as In the other 

 instances, by the relation of the shell to the animal when In motion ; 

 and the parts enclosed by the spiral shell should be regarded as simply 

 a hernia of the viscera through the back of the animal. 



There were other terms also, which he showed to be unsuitable, 

 having been derived from a false idea of use, or from a fanciful analogy. 

 Thus the mouth and throat and teeth and lips of a shell are spoken of, 

 which terms might be allowable, were it not that there is an animal in 

 all cases which should properly be considered in the full description, 

 and which has all these parts performing their legitimate offices. He 

 pursued the subject In this direction with various examples and 

 suggestions. 



The Custodian announced the presentation of a sei-ies of 

 thirty-three casts of Mexican masks from the Smithsonian 

 Institution, which were exhibited on the table. 



