BILLINGSELLID^. 771 



same horizon as that of No. 31c, just south of the south fork of Paradise Dry Canyon (locally known as East Fork), east 

 of Paradise, Cache County; and (33r) limestones faulted against the Cambrian quartzites in a canyon about 1 mile {1.6 km.), 

 east of Cricket Spring, Cricket Range (locally known as the Beaver River Range or the Beaver Mountains), northwest of 

 Blackrock, Millard County; all in Utah. 



Genus WYNNIA Walcott." 



PTt/mwa Waicott, 1908, Smithsonian Misc. Coll., vol. 53, No. 4, PI. XI, and pp. 142 and 148. (Classification of genus.) 

 The description of the type species includes all that is known of this genus. The material 

 is poor, but sufficient to indicate that the species belongs to an undefined genus. It differs 

 from OrtJiis (restricted) in the presence of the large vascular sinuses of the ventral valve and 

 pointed apex of the dorsal valve. The latter is of the type of the apex of the valves of Nisusia 

 festinata (Billings). From Billingsella it differs in the absence of dental plates and deltidium 

 in th^ ventral valve. 



Type. — OrtMs warthi Waagen. 



The generic name is given in honor of Mr. Arthur B. Wynne, of the Geological Survey of 

 India. 



L Wynnia waethi (Waagen). 



Text-figures 68A-A'; Plate LXXXIX, figures 4, 4a-f. 



Orthis warthi Waagen, 1891, Mem. Geol. Survey India, Paleontologia Indica, 13th ser.. Salt Range Fossils, vol. 4, 

 pt. 2, pp. 102-104, PI. I, figs. 12-15, PI. II, figs. 1 and 2. (Described and discussed as a new species. The 

 specimen represented by fig. 12b is redrawn in this monograph, PL LXXXIX, fig. 4a. The specimen repre- 

 sented by fig. 14 is redrawn in the same position on PL LXXXIX (fig. 4b) of this monograph and in text fig. 68A'. 

 Different views of the same specimen are shown in this monograph, PL LXXXIX, fig. 4, and text fig. 68A, both 

 of which drawings are of the same shell in the same position. The 

 text figures are the correct representations in each case. PL II, 

 figs. 2a, 2b, and 2c, are copied in this monograph, PL LXXXIX 

 figs. 4e, 4d, and 4f, respectively.) 



Shell small, biconvex, subcircular to broad oval in 

 outline. Exterior surface unknown. Cast of interior of 

 ventral valve strongly convex. Apex slightty incurved 

 over a rather high area that slopes forward at an angle of 

 about 45° to the hinge line. The area is formed of two p,^,,,,, ..^ ^,„^■ „.,„r , , ^ . , 



*=■ . . iiGUKE 08.— Hynmia wart/u (Waagen). A, Cast of 



narrow sides separated by a large triangular delthyrium interior of a ventral valve (x 4). Thesheiiwas 



without traces of a deltidium; the narrow, elongate sides compressed laterally and hence the muscle .sears 



' _ . ''°" smuses are crowded toward the center. 



are slightly concave and have in the cast a narrow raised a', Posterior view of same specimen, showing 

 margin next to the delthyrium. The dorsal valve is less broken-oa heak. 



,1 , , , 1 • , 1 c II. ,1 The specimen from which figures 6SA and 68 A' 



convex than tlie ventral, its area slopes forward from the are drawn is incorrectly figured on PlateLXXXIX, 



hinge and at the apex of the valve bends slightly forward, figures 4 and 4b, of this monograph, and is the speei- 



. r „, ^ UiT1it,v.£j.i ^1 1 £ men figured by Waagen [1S91, PI. II, fig. 14]. It is 



givmg an effect somewhat like that of the ventral valve of trom the upper portion of the "Neoboius beds" at 

 Nisusia festinata (Billings), only very much reduced. The ^^^^ h"'- ^^^ ^™R«' ^'^'^ ('^™'- S"''™? India, 



~ , . . „ , ,1 , Cat. No. 4/124). 



casts of the interior of the ventral valve sfiow two strong 



vascular sinuses and a faintly defined muscle area. This has an outline not unlike that of the 

 diductor scars in the ventral valve of Billingsella romingeri (Barrande) (PI. XC, fig. 2g). The 

 large main vascular sinuses also extend forward in the same manner in the two species. The 

 illustrations of the interior of the ventral valve of Wynnia warthi (PI. LXXXIX, figs. 4 and 4a) 

 fail to show the outline of the muscle area as well as it is shown in the specimen represented 

 by figure 4, so I have inserted text figures 68A and 68A', which are drawn from the same 

 specimen. 



The casts of the interior of the dorsal valve show a median depression with a few radiating 

 lines, and a few very fine radiating lines extending from the apex a short distance forward. 

 In addition, by reflected light, the outlines of the anterior and posterior adductor scars can 

 be seen on the posterior half of the valve (PI. LXXXIX, fig. 4c). 



The longest ventral valve in the collection has a length and width of 9 mm. The dorsal 

 valve is a little shorter. 



a Prior to the definition of the genus Wynnia the type species was placed under Ortlris [Waagen, 1891, p. 102]. 



