19 



7. Melania inquinata, a specimen to show the form of the outei 



lip, comparatively with fig. 4. 

 a. a. The space between the posterior tubercular ridge and the 



suture, 

 i. I). Distinct lines of growth showing the form of the outer 



lip, comparatively with b. b. of fig. 4. 



Art. II. RiXTiFiCATioN of some mistakes relative to the Genera Crania 

 Retzius and Orbicula of Lamarck, which have been committed 

 by various Authors : by G. B. Sowerby, F.L.S., &c. 



That men of science and naturalists are every day more and more fully 

 convinced of the necessity of exactness or precision, is proved by the 

 comparative care and attention to minutias with which their researches 

 are conducted at the present time, in contradistinction to the apparent 

 negligence and inattention to important circumstances, which formerly 

 characterized their discriminations. Even geologists, who formerly paid 

 so little attention to specific differences, and who considered every fossil 

 without exception as a result of the Noachian deluge, appear now to 

 think it necessary before drawing their conclusions, to make themselves 

 acquainted with the generic and specific distinctions of the fossils which 

 characterize different geological periods, inaismuch as they find that their 

 conclusions may be in a greater or less degree confirmed or invalidated 

 in proportion to the exactness with which they may have deduced them 

 from facts. It is now well known that every thing in nature is governed 

 by fixed laws, therefore those who wish to become acquainted with her 

 works must be extremely precise and attentive in their pursuit of this 

 knowledge. 



For this reason, when I am convinced that any of my fellow students 

 have, in consequence of carelessness or inattention in conducting their 

 researches, arrived at incorrect conclusions, I consider it to be my duty 

 to endeavour, if in my power, to set them right ; and for the same 

 reason I am happy when any who are farther advanced in any particular 

 branch-of thi.; study than I am, think so well of my labours as to take 



