262 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 53 



Mesonacis Weller, 1900, Ann. Rept. Geol. Survey, New Jersey, for 1899, 

 PP- 50-51- (Discussed.) 



Schmidtiellus Moberg, in Moberg and Segerberg, 1906, Meddelande fran 

 Lunds Geologiska Faltklubb, Ser. B, No. 2 (Aftryck ur Kongl. 

 Fysiografiska Sallskapets Handlingar, N. F., Bd. 17), p. 35, footnote. 

 (Proposed as a new genus by Moberg for Schmidtia Marcou, pre- 

 occupied.) 



Type of the genus Mesonacis vermontana Hall. The description 

 of the genus is incorporated with that of the type species [Walcott, 

 1886, pp. 158-162], and its relations are discussed in this paper under 

 observations on the Mesonacid?e (pp. 244, 246, and 250). 



MESONACIS MICKWITZI (Schmidt) 

 Plate 26, Fig. 4, Text Figs. 16 and 17. 



Olenellus mickwitzi Schmidt, 1888, Mem. Acad. Imp. Sci. St.-Petersbourg, 

 7th ser., Vol. 36, No. 2, pp. 13-19, pi. i, figs. 1-25. (Described and 

 discussed. Figure i, with the exception of the cephalon which was 

 added from other specimens, is copied in his paper, pi. 26, fig. 4.) 



Olenellus mickivilzi Schmidt, 1889, Melanges Geol. et Paleontol. tires du 

 Bull. Acad. Imp. Sci. St.-Petersbourg, N. S., Vol. i {2)2))^ PP- IQI-IQS. 

 10 text figures on page 193. (Described and discussed, giving addi- 

 tional details. Figures i and 9 are copied in this paper as text figures 

 16 and 17, p. 263.) 



Elli otocephalus {Schmidtia) mickivitsi (Schmidt), Marcou, 1890, Amer- 

 ican Geologist, Vol. 5, p. 363. (The subgenus Schmidtia is proposed 

 for this and other species.) 



Olenellus (Mesonacis) mickwit::i (Schmidt), Walcott, 1891, Tenth Ann. 

 Rept. U. S. Geol. Survey, p. 634, pi. 93, fig. i. (Merely refers the 

 species to Mesonacis and copies Schmidt's restoration [1888, pi. i, fig. 

 I]-) 



Mesonacis mickzvitzice Peach, 1894, Quart. Journ. Geol. Soc. London, 

 Vol. 50, p. 672, text fig. B, p. 673. (Mentioned. The text figure is 

 copied from a part of one of Schmidt's figures.) 



Olenellus (Mesonacis) mickzvitzi Frech, 1897, Additional plates inserted 

 in 1897 in Lethsea geognostica, Pt. i, Lethjea palaeozoica. Atlas, pi. la, 

 fig. 8. (Figure 8 is copied from Schmidt, 18S8, pi. i, fig. i.) 



Schmidtia mickwitzi (Schmidt), Moberg, 1899, Geol. Foren. i Stockholm 

 Forhandl., Bd. 21, Hafte 4, pp. 319-320, pi. 13, figs. Va-c. (Described 

 and discussed; figure Va is copied from Schmidt [1888, pi. i, fig. i] 

 and figures Vb and Vc are copied from Schmidt [1889, figs, i and 9, 

 P- 193]-) 



Schmidtiellus mickzvitzi Moberg, in Moberg and Segerberg, 1906, Medde- 

 lande fran Lunds Geologiska Faltklubb, Ser. B, No. 2 (Aftryck ur 

 Kongl. Fysiografiska S.^llskapets Handlingar, N. F., Bd. 17), p. 35, 

 footnote. (Merely proposes the new generic name Schmidtiellus for 

 this species, Schmidtia Marcou being preoccupied.) 



