PATERINIDiE. 359 



IPHIDELIiA Walcott, a subgenus of MICBOMITRA. 



[Iphidea.] 



Kutorgina Walcott (in part) [not Billings], 1886, Bull. U. S. Geol. Survey No. 30, pp. 101-102. (Genus Kutorgina 

 described, but description also includes reference to specimens now referred to Micromitra, Micromitra (Paterina), 

 and Micromitra (Iphidella).) 



Kutorgina Hall and Clarke (in part) [not Billings], 1892, Nat. Hist. New York, Paleontology, vol. 8, pt. 1, pp. 90-94. 

 (Copies Walcott's description, 1886b, pp. 101-102, and discusses genus, but description and discussion also include 

 reference to specimens now referred to Micromitra, Micromitra (Paterina), Micromitra (Iphidella), Protorthis, and 

 Billing sella.) 



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

 cussed includes species now referred to Mia-omitra, Micromitra (Paterina), and Micromitra (Iphidella).) 



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 mth Micromitra, Micromitra (Paterina), and Micromitra (Iphidella).) 



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

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



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

 tion of subgenus.) 

 IpTiidella was proposed to replace Iphidea, no species being given as the type. Micromitra 



Meek [1873, p. 479] has prioritj' as the generic name, but as Iphidella was intended to inckide 



the ornamental crenulated as well as plain tj^pe of surface, those species having the former tj^pe 



are now grouped under Iphidella as a subgenus of Micromitra. 

 Type. — Trematis pannulus Wliite. 

 The species included in this subgenus and the description of their ornamented surfaces are 



given under the description of Micromitra (p. 336). . 



Micromitra (Iphidella) louise Walcott. 



Text figures 31A-B. 



Micromitra (Iphidella) louise Walcott, 1908, Smithsonian Misc. Coll., vol. 53, No. 3, pp. 56-57, PL VII, figs. 4 and 4a.' 

 (Discussed as below as a new species. Figs. 4 and 4a are copied in this monograph as figs. 31A and 31B, .respec- 

 tively.) 

 In form tliis species is not unlike Micromitra pealei (PL III, figs. 3, 3a-e) and the more 



elongate form of Micromitra {Iphidella) pannula maladensis (PI. IV, figs. 2, 2a-g). It differs 



from both forms mentioned in its surface characters. In the 



latter respect it is more hke M. (/.) nyssa (PI. Ill, figs. 9, 9a), 



but the form of M. (I.) louise is more elongate and the apex 



of the ventral valve is nearer to the posterior margin; the shell 



also appears to have been thicker. The surface characters are 



exceedinglyminute. Under a glass magnifying twentj' diameters 



the surface looks much like that of the anterior half of Plate 



IV, figure Is. The largest ventral valve in the collection has a figure si.— Micromitra (iphidaiayiouiseWai- 



, ,!»__ i' -liij^rr 1 i- 1 cott. A, Flattened and partly distorted ven- 



length of 7.5 mm. and a width of 7 mm.; elevation, 1 mm. traivai™, the type speciinen(u.s.Nat.Mus. 



Micromitra {Iphidella) louise is the oldest known brachiopod cat. No. suoia.) b, side of laterally com- 



- ,1.^ ,. p ,T r^ T -f-, ^ -\r , • t,i pressed ventral valve (U. S. Nat. Mus. Cat. 



from the Cambrian or the Canadian Kocky Mountains, in the no. aiwib). 



Lakes Louise and Agnes section it is 3,150 feet (960.1 m.) The specimens represented are Irom the 



below the Middle Cambrian, and 2,760 feet (841.2 m.) below Lower Cambrian siliceous Lake Louise shale, 



' 1 1 . J! 7 . ^* Locahty 3Sd, on the north side of Lake 



the horizon which is correlated on the basis of the associated Louise, Alberta, Canada. The figures are 



faunas with that at which M. (/.) nyssa occurs in Montana, "^^f^ ^""^ '*^'^''=°" [""^'i' ^'- "^"' ^^'- * 



It occurs in a fine, hard, dark-gray, siliceous shale in 



association with Hyolithes, Cruziana, and a fragment indicating the free cheek of a trilobite. 



a The synonymy for this subgenus does not give a complete record of the various genera under which the species now included in Iphidella were 

 formerly placed; it includes only those references in which the subgenus is discussed or described. For the sake of completing the record the 

 remaining mere generic references are here listed: 



Trematis White [1S74, p. 6]. 



Iphidea Linnarsson [1876, p. 25]. 



Trematis White [1877, p. 36]. 



Kutorgina Walcott [1887, p. 190; 1891a, p. 609]. 



Iphidea Schuchert [1897, p. 234]. 

 Iphidea Matthew [1902b, p. IIOJ. 

 Iphidea Gronwall [1902, p. 40). 

 Kutorgina Pack [1906, p. 296). 



