266 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 53 



Olenellns vermontaiia (Hall), Holm, 1887, Geol. Foren. i Stockholm 

 Forhandl., Bd. 9, Hafte 7, pp. 515-516. (Described in Swedish. The 

 species is frequently mentioned also in the discussion of " Olencllus 

 kjeriM.") 



EUiptocephalus (Schmidtia) vemiontana Marcou, 1890, American Ge- 

 ologist, Vol. 5, p. 363. (The subgenus Schmidtia is proposed for this 

 and other species.) 



Olenellus (Mesonacis) vermontaiia (Hall), W.xlcott, 1891, Tenth Ann. 

 Rept. U. S. Geol. Survey, p. 637, pi. 87, figs, i, la-b. (No text reference. 

 Figure i is copied from Hall, 1859, fig. 2, p. 60; and figures la and ib 

 are copied from Walcott, 1886, pi. 24, figs. la and ib.") 



Olenellus {Mesonacis) vermontana (Hall), Cole, 1892, Natural Science, 

 Vol. I, pp. 340 and 341, fig. 2, p. 343. (Discussed. The figure is an 

 outline drawing of the figure given by Walcott, 1886, pi. 24, fig. la.) 



Mesonacis vennontana Moberg, 1899, Geol. Foren. i Stockholm Forhandl., 

 Bd. 21, Hafte 4, p. 318, pi. 13, fig. 4. (Mentioned at several places in 

 the text. The figure is copied from Walcott, 1886, pi. 24, fig. la.) 



A detailed description of this species was given in 1886 [Wal- 

 cott, 1886, p. 158]. Nothing has been added to our information of 

 it since that date and no additional specimens have been discovered. 

 The finding of a specimen of Pcedcmnias transitans in association 

 with Mesonacis vermontana at Georgia, Vermont, in which three 

 rudimentary segments and a Mesonacis-like pygidium occur beneath 

 the telson [pi. 33, fig. i] corroborated the view held in 1886 [Wal- 

 cott, 1886, p. 166] that the body of Mesonacis was shortened by the 

 absorption of the posterior segments and the spine on the fifteenth 

 segment became the elongate telson of Olenellus. At first I was 

 inclined to refer the form with the three rudimentary segments to 

 Mesonacis, but with the discovery at York, Pennsylvania, by Prof. 

 Atreus Wanner, of numerous specimens with from two to six rudi- 

 mentary segments, and that all the rudimentary segments were un- 

 like those of Mesonacis vermontana, I decided finally to include such 

 specimens in a new genus Pcedeumias, and to retain in Mesonacis 

 only those specimens that have only normal thoracic segments pos- 

 terior to the fifteenth spine-bearing segment. 



Formation and Locality. — Lower Cambrian: (25) siliceous 

 shale just above Parkers quarry, near Georgia, Franklin County, 

 Vermont. 



Specimens corresponding to the cephalon of this species occur at 

 Bonne Bay, Newfoundland, and L'Anse au Loup, on the north side 

 of the straits of Belle Isle, Labrador. 



