OLENELLUS AND OTHER GENERA OF MESONACID.E 26 1 



Genus MESONACIS Walcott 



Barrandia Hall (in part), i860, Thirteenth Ann. Rept. New York State 

 Cab. Nat. Hist., p. 115. (Described and discussed. As described the 

 genus includes forms now referred to both Mesonacis and Olenellus. 

 Beginning with the 5th paragraph the text is a description of " Bar- 

 randia thompsoni.") 



Barrandia Hall (in part), 1861, Report on the Geology of Vermont, Vol. 

 I, p. 369. (Copy of Hall, i860, p. 115; the reference includes species 

 referred to both Mesonacis and Olenellus. Beginning with the 5th 

 paragraph the text is a description of the species "Barrandia thomp- 

 soni"; this is also copied from the preceding reference.) 



Olenellus Ford (in part), 1881, American Journ. Sci., 3d ser., Vol. 22, p. 

 251. (As discussed in this paper the genus Olenellus includes forms 

 now referred to Elliptocephala, Mesonacis, and Olenellus.) 



Mesonacis Walcott, 1885, American Journ. Sci., 3d ser., Vol. 29, pp. 328- 

 330. (Discussed as a new genus.) 



Mesonacis Walcott, 1886, Bull. U. S. Geol. Survey, No. 30, p. 158. (Merely 

 gives its position in the classification of the trilobites.) 



Olenellus Holm (in part), 18S7, Geol. Foren. i Stockholm Forhandl., Bd. 

 9, Hafte 7, pp. 498-499. (Described in Swedish. As described and 

 discussed throughout the paper, the genus includes many of the forms 

 now placed in the family Mesonacidae.) 



Elliptocephalus (Schmidtia) Marcou (in part), 1890, American Geologist, 

 Vol. 5, p. 363. (Schmidtia is proposed as a new subgenus to include 

 forms that are now referred to Mesonacis mickzvitsi, Mesonacis 

 vermontana, and Zac'anthoides typicalis.) 



Not Schmidtia Voleorth [i860] = Brachiopod. 



Not Schmidtia Bals-Criv. = Protozoan. 



Olenellus (Mesonacis) Walcott, 1891, Tenth Ann. Rept. U. S. Geol. 

 Survey, p. 637. (Mesonacis is here placed as a subgenus of Olenellus. 

 The forms referred to the subgenus are now placed under both Meso- 

 nacis and Elliptocephala. 



Mesonacis Cole, 1892, Natural Science, Vol. i, pp. 342 and 344. (Discussed. 

 In the legend of figure 2, p. 343, Mesonacis is placed as a subgenus of 

 Olenellus.) 



Mesonacis Peach and Horne (in part), 1892, Quart. Journ. Geol. Soc. 

 London, Vol. 48, p. 236. (As defined this genus includes forms now 

 referred to both Elliptocephala and Mesonacis.) 



Mesonacis (Olenellus) Peach, 1894, Idem, Vol. 50, pp. 671-674. (As 

 discussed in these pages this genus includes forms now referred to 

 both Elliptocephala and Mesonacis.) 



Elliptocephala (Mesonacis) Bf.echer, 1897, American Journ. Sci., 4th sen, 

 "Vol. 3, p. 192. (Mesonacis is stated to be probably of only subgeneric 

 value under Elliptocephala.) 



Mesonacis Moberg, 1899, Geol. Foren. i Stockholm Forhandl., Bd. 21, 

 Hafte 4, p. 318. (Described in Swedish. The genus is discussed 

 frequently on pages 309-320 of the paper.) 



Schmidtia Moberg, 1899, Idem, p. 319 and footnote. (Discussed in Swed- 

 ish.) 

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