344 CAMBRIAN BRACHIOPODA. 



Billings, Walcott (in part), 1897, Proc. TJ. S. Nat. Mus., vol. 19, pp. 707-711. (Discussed. The genus as 



discussed includes species now referred to Micromitra, Micromitra (Paterina), and Mieromitra (Iphidella).) 

 Patenna Beecher, Walcott, 1897, idem, p. 708. (Discussed as synonym of Iphidea.) 

 Iphidea Billings, Schucheet (in part), 1897, Bull. U. S. Geol. Survey No. 87, p. 233. (Merely refers Micromitra and 



Paterina to Iphidea.) 

 Iphidella Walcott (in part), 1905, Proc. U. S. Nat. Mus., vol. 28, p. 304. (Merely proposed to replace Iphidea, but 



includes reference to specimens belonging with Micromitra, Micromitra (Paterina), and Micromitra (Iphidella) .) 

 Iphidea Billings, Grabau and Shimek (in part), 1907, North American Index Fossils, vol. 1, p. 201. (Described, and 



includes species referred to each of the subgenera Paterina and Iphidella.) 

 Micromitra (Paterina) (Beecher), Walcott, 1908, Smithsonian Misc. Coll., vol. 53, No. 4, PL XI, and pp. 142 and 143. 



(Classification of subgenus.) 



All of the species of Micromitra with plain concentric striae on the outer surface are grouped 

 under Paterina as a subgenus. Beecher [1891, p. 345] quoted " Oholuslahradoricus Billings" as 

 the type of liis genus Paterina, supposing that the species represented the simplest form of 

 brachiopod known. The genus was subsequently shown [Walcott, 1897b, p. 707] to have been 

 previously described [Meek, 1873, p. 479] under a different name, Micromitra {Iphidea being 

 preoccupied [Schuchert, 1905, p. 329]), but as it appears necessary to group the shells of which 

 Micromitra (Paterina) labradorica (Billings) is a typical example under a subgenus, I have 

 adopted Paterina as the name for it. 



Type. — Kutorgina labradorica swantonensis Walcott [1890, p. 36]. 



Beecher studied the specimens of the variety Micromitra (Paterina) labradorica swantonensis 

 (Walcott) which were in my laboratory in the United States National Museum and did not at 

 the time have the specimens of "Obolus labradoricus" from the St. Lawrence Valley. He 

 mistook the duplicate specimens of the variety for the species, and it was from the material he 

 examined that the area of the ventral valve was subsequently worked out, as shown on Plate 

 II, figures 3d, 3e, and 3f. 



A Hst of the species referred to Paterina has been given under the genus Micromitra (p. 336). 



I 



MicEOMiTRA (Paterina) sella (Billings). 

 Plate II, figures 1, la-c. 



Iphidea bella Billings, 1872, Canadian Naturalist, 2d ser., vol. 6, No. 4, pp. 477-478, fig. 13. (Described and discussed 



as a new species; see p. 345, for copy. Fig. 13 is reproduced in this monograph, PL II, fig. Ic.) 

 Iphidea bella Billings, 1874, Geol. Survey Canada, Paleozoic Fossils, vol. 2, pt. 1, p. 76, fig. 44. (Description and 



figure copied from preceding reference.) 

 Iphidea bella Billings, 1882, Geol. Survey Newfoundland, Rept. Progress for 1881, Appendix, p. 13, fig. No. 8. (A 



copy of the preceding reference.) 

 Iphidea bella Billings, Walcott, 1886, Bull. U. S. Geol. Survey No. 30, p. 100, PL VII, fig. 4. (Copies the original 



description, Billings, 1872b, pp. 477-478, and discusses species. Fig. 4 is copied from Billings, 1872b, fig. 13, 



p. 477.) 

 Iphidea bella Billings, Okhlbet, 1887, Manuel de conchyliologie, by Fischer, p. 1270, fig. 1026. (Mentioned in 



French. Fig. 1026 is copied from Billings, 1872b, fig. 13, p. 477.) 

 Iphidea bella Billings, Walcott, 1891, Tenth Ann. Rept. U. S. Geol. Survey, p. 608, PL LXVII, fig. 6. (Mentioned. 



Fig. 6 is copied from Billings, 1872b, fig. 13, p. 477.) 

 Not Iphidea bella Hall and Clarke, 1892, Eleventh Ann. Rept. State Geologist New York, for 1891, p. 249, PL IV, 



figs. 4 and 5. (Mentioned. Referred in this monograph to Micromitra (Paterina) labradorica sivantonensis.) 

 Iphidea bella Billings, Hall and Clarke (in part), 1892, Nat. Hist. New York, Paleontology, vol. 8, pt. 1, p. 98, fig. 



54, not PL IV, figs. 8 and 9. (Mentioned in the text. Fig. 54 is copied from Billings, 1872b, fig. 13, p. 477. 



The specimens represented by figs. 8 and 9 are referred in this monograph to Micromitra (Paterina) labradorica 



swantonensis.) 

 Iphidea bella Billings?, Geabau, 1900, Occas. Papers Boston Soc. Nat. Hist., No. 4, vol. 1, pt. 3, pp. 617-618, PL XXXI, 



fig. 2. (Described and discussed.) 

 Micromitra bella (Billings), Clark and Mathews, 1906, Maryland Geol. Survey, vol. 6, pt. 1, p. 252, PL XVI, fig. 15. 



(No text reference. Fig. 15 is copied from Walcott, 1886, PL VII, fig. 4.) 

 Iphidea bella Billings, Geabau and Shimee, 1907, North American Index Fossils, vol. 1, p. 201, fig. 234h, p. 199. 



(Described. Fig. 234h is copied from Billings, 1872b, fig. 13, p. 477.) 



The shell described and illustrated by BiUings [1872b, pp. 477-478] had a large false area 

 and a convex pseudodeltidium, the width of which at the hinge hne was stated to be nearly 

 one-third the whole width of the shell. 



