280 THE AMERICAN MONTHLY [December, 



ter is correct in the text, even he is just as much at fault in his figures, 

 probably because he did not draw them himself. For in those figures 

 also there is the same lack ; the one important point is not indicated 

 that one valve with its hoop fits into the other valve with its hoop. So 

 that the student will find himself bothered enough if he tries to recon- 

 cile the text and the drawings. The president of the N. Y. Mic. Soc. 

 at a meeting on January 7, 1881, also stated the matter correctly, but 

 no drawings are appended to the report of that meeting in the Mlc7'os. 

 Jour.^ and the report is besides in fine print and apt to be overlooked. 

 In fact, I know of only one man who has correctly drawn the valves in 

 front view, and that is Schmidt, in his atlas of the Diatomacea^. (Since 

 writing the above I have found, however, that Rev. Wm. Smith, H. 

 L. Smith, and Greville have done so.) If the student has access to 

 Schmidt's plates and will look at his figures of Navicula pachyptera 

 (No. 5, pi. 45), Nav. distans (No. 14, pi. 46), Nav. northuinbrica 

 (No. 19, pi. 47), and other NaviculcE (Nos. 7 and 9, pi. 48), and es- 

 pecially at those of Aulacodiscus scaber (No. 6, pi. 33) , Aulacodiscus 

 kittonii (No. 6, pi. 41), and those of 7rice7'atiu7n on pi. 77, he will 

 see the difference between them and the figures in the AIiC7'ograpJiic ox 

 Carpenter at a glance. For in Schmidt's plates, by the uneven edges 

 and by the double line for a part of the edge, it is plainly shown that 

 the one valve with its hoop is enclosed in the other valve with its hoop. 

 Yet even in this atlas the student might readily overlook the fact ; for 

 though there are over 1,500 diatoms figured there, among them all there 

 are only about 10 which show this point distinctly ; and unless the stu- 

 dent is more than commonly observing, or has had his attention called 

 to this matter, it will probably make no impression. 



\To be continued^). 



List of all Pjitents for Improving the Microscope issued in the 

 United States from 1853 to 1890. 



1853. H. De Riomondie. Otoscope (No. 9,581). 



1 86 1. R. P. Dagron. Photo charm (No. 33,031). 



1862. H. Craig. Charm (No. 34,409). 



1864. J. Ellis. Seed microscope (No. 42,843). 



1865. Wales. Plain movable front to lens (No. 46,511). 

 1865. J. J. Bausch (No. 47,382). 



1865. C. B. Richards. Friction wheels on rack motion (No. 47,860). 



1866. H. L. Smith. Side reflector above objective (No. 52,901). 

 1866. Heath. Combined microscope, telescope, and eye glass (No. 



54^542). 



1866. R. B. Tolles. Binocular eye-piece (56,125). 



1866. O. N. Chase. Seed glass (No. 56,178). 



1869. J. H. Logan. Dissecting microscope (No. 93,895). 



1874. J. J. Bausch. Botanical microscope (No. 151,746). 



1876. Wales' pillar fine adjustment (No. 178,391). 



1876. J. Zentmayer. Fine adjustment carrying rack, swinging sub- 

 stage (No. 181,120). 



1876. Gundlach. Fine adjustment (No. 182,919). 



1877. Gundlach. Glass stage, sliding carrier (No. 198,607). 



1878. R. B. Tolles. Sector illuminator (No. 198,782). 



