FiGTiKE 25.— Micromitra 



PATEKINID^. 351 



The conglomerates of tliis formation, according to Logan, form 9 separate layers, from 2 

 to 16 feet tliick, bedded in gray calcareous sandstone. The geologic age of the deposit of the 

 matrix is supposed to be Upper Cambrian or Lower OrdoTician. The age of the bowlders can 

 only be determined by the fossils found in each. 



The specific name was given in honor of Sir Wilham E. Logan. 



Formation and locality. — Middle? Cambrian: (2n) Limestone in conglomerate on shore near Trois Pistoles, 

 on St. Lawi-ence River, Province of Quebec, Canada. 



Micromitra (Paterina) major (Walcott). 



V 



Text figure 25. 



Iphidella major Walcott (in part), 1905, Proc. U. S. Nat. Mus., vol. 28, p. 304. (Described and discussed somewhatas 

 below as a new species. Specimens now referred to MicroTnitra {Paterina) williardi were included with the 

 specimens representing Micromitra (Paterina) major when this description was given.) 



Obolus smithi Walcott (in part), 1908, Smithsonian Misc. Coll., vol. 53, No. 3, PL VII, fig. 9 (not fig. 9a, which rep- 

 resents a specimen of Obolus smithi). (No text reference. Fig. 9, which is reproduced in this monograph as 

 fig. 25, was inserted on PL VII of the above reference by mistake. All of the figures representing the two species 

 (Obolus smithi and Micromitra (Paterina) major) happened to be grouped on the same preliminary plate, and 

 when two figures were chosen to represent Obolus smithi in the paper referred to, one of the figures representing 

 Micromitra (Paterina) "major was accidentally included.) 



Ventral valve subcorneal, with the apex slightly in front of the posterior margin. A 

 minute beak appears to incurve over the pseudodeltidium. Cardinal slope 

 rather abruptly rounded, so as to indicate a rather narrow false area. 

 Pseudodeltidium broad and convex, with its lower margin arched so as to 

 leave a space between it and the plane of the margin of the shell. Dorsal 

 valve slightly convex, with a narrow area. 



Surface, so far as can be determined from the badly preserved mate- 

 rial, marked by rather strong growth lines and very fine concentric striae. (Paterina) major (Wai 

 The largest dorsal valve has a length of 10.5 mm.; width, 13 mm. Only ™"'efroi?Lo1amy"6c! 



one small ventral valve is kno^vn. Lower Cambrian beds in 



^7 .. rni J ■ 1 J ■ ii • • • 1 Rome formation ("Mon- 



Ooservahons. — ihe material representing this species is more or less tevaiioshaie"),i.i25miies 

 compressed and distorted in the argillaceous shales in which it occurs. ''•* '^™-' "ortheast of 



T If • ■ Ti T e Tir- • /T-i • \ T 1 -I • Helena, Shelby County, 



in general form it is not unlike that or Micromitra (Fatenna) Laoradonca Alabama (u. s. Nat. 

 (Billings) (PL II, figs. 2, 2a-f), but it differs m its nearly smooth surface mos. cat. No. 51499). A 



, , . . „ , . • 11. This figure was published 



and the position of the apex, it is, however, the southern Appalachian [Waioott,i908d,pi.vn,flg. 



representative of that species. The original description of this species was vlh4Tf'^06o*«s°5!f/^;i1°and 



based on specimens now referred to this species and to Micromitra {Pater- was given cat. No. 5iciia. 



ina) williardi Walcott. Very good specimens of the latter are now avail- under'thTs'econ'd reference 



able from two localities near Helena, Alabama. ^ w^'' synonymy, tws was 



rr^T • e • -n -1 • a mistake. 



ihis lorm owes its specific name to its large size. 



Formation and locality. — Lower Cambrian: (56c) Rome (" Montevallo") formation along road just north of Buck 

 Creek, 1.125 miles(1.8 km.) northeast of Helena; and (17b) Rome ("Montevallo") formation 4 miles (6.4 km.) south of 

 Helena; both in Shelby County, Alabama. 



A dorsal valve similar to the one illustrated above occurs at the following locality: 



Middle Cambrian: (90) Conasauga ("Coosa") shale on Edward's farm, near Craigs Mountain, about 10 miles (16.1 

 km.) southeast of Center, Cherokee County, Alabama. 



Micromitra (Paterina) phillipsi (HoU). 



i/ Plate III, figure 8. 



Obolella phillipsi Holl, 1865, Quart. Jour. Geol. Soc. London, vol. 21, pt. 1, p. 102, figs. lOa-c. (Described as a new 



species. The specimen represented by figs. 10b and 10c is redrawn by Davidson, 1866, PL IV, figs. 17a and 17c, 



and Davidson's figures are copied in this monograph, PL III, fig. 8.) 

 Obolella ? phillipsi Holl, Davidson, 1866, British Fossil Brachiopoda, vol. 3, pt. 7, No. 1, pp. 62-63, PL IV, figs. 17-19. 



(Described and discussed. Figs. 17a and 17c are drawn from the specimen represented in figs. 10b and 10c of 



the preceding reference, and are reproduced in this monograph, PL III, fig. 8.) 

 Kutorgina cingulata Davidson [not (Billings)], 1868, Geol. Mag., vol. 5, p. 312, PI. XVI, fig. 10. (Discussed.) 



