Micro. 



404 



. '''^'^Tv 



Microdiscus dawsoni, (Hartt, in Acad. Geol.) Walcott, 



Bulletin, U. S. G, S. No. 10, page 23, pi. 2, 

 fig. 3, head shield enlarged three times ; 

 fig. 3 a, tail shield enlarged three times. — 

 Middle Camhrian {Saint John) New 

 Brunswick, M, C. 



Microdiscus lobatus. {Agnostus lohatus^ Hall, 1847, Pal. 



^ N. Y. Vol. 1, p. 

 M^e. J Jl^ 'l^ P»' i6 258, pi. 67, figs. 5^. 



—f.) Ford, 1873, 

 Amer. Jour. S.[3.] 

 vi,135, foot note. — 

 Walcott, Bull. U. 

 S. G. S. No. 30, 

 page J 56, plate 16, fig. 1, head very much enlarged; 

 1(Z, another head, to show range of variation; Ih tail (pygi- 

 dium) very 'much enlarged, — Found in the Low. Camlrian 

 ( Georgian) formation, — multitudes of them occurring in the 

 conglomerate limestone on the ridge east of Troy, N. Y. — Note. 

 Formerly considered characteristic of Hudson river slate forma- 

 tion. See Agnostus lohatus., above. L. C. 



Eogers, page 820, fig. 614. {Beyrichia lolata.) Middle Cam- 

 Wlk./^M^^ brian. (Formerly considered a Hudson river 

 (Loraine) formation species (III b.) Described 

 as a Beyrichia, but it is a trilobite. Figs. 1 

 n ^^s//:|A show the natural size, figs. 2, enlarged. 



Microdiscus meeki, (Ford, Am. J. S. [3] xi, 371.) Wal- 



^ cott. Bull. U. S. G. S. No. 30, page 155, plate 16, 



^ fig. 4, head (drawn by S. W. Ford) this, the only 



specimen found, necessarily stands as the type of 



the species ; Lower Camhrian conglomate limestone 



in ridge east of Troy, N. Y. — L. C. 



Microdiscus parkeri, Walcott, Bulletin, U. S. G. S. No. 



30, plate 16, fig. 2 and 2(^5, head and 

 tail, enlarged Hve times. — Georgian 

 i^ formation ; Parker's Trilobite 

 quarry, north of Georgia Plains, 

 Franklin Co., Vermont. — Z. C. 



