OBOLID^. 529 



LiNGULELLA RADULA MattlieW. 

 Plate.XLV, figures 1, la-1. 



Lingulella radula Matthew, 1891, Trans. Roy. Soc. Canada, 1st ser., vol. 8, sec. 4, ISlo. b, pp. 147-148, PL XV, figs. 

 7a-b and 8a-e. (Described and discussed as a new species. PI. XLV, figs. 1, la, lb, Ic, and le, are drawn 

 from specimens in Matthew's type material, but further identification is impossible.) 



Lingulella radula aspera Matthew, 1903, Geol. Survey Canada, Rept. Cambrian Rocks Cape Breton, pp. 204-205, 

 PI. XV, figs. 2a-d. (Described and discussed as a new variety.) 



General form ovate cuneate, with the ventral valve subacuminate and the dorsal valve 

 broadly ovate in outline; valves apparently moderately convex, but this is uncertain, as the 

 shells have all been compressed in the arenaceous shale. Surface marked by concentric lines 

 of growth and very fine, irregular striae. It is the type of surface of Oholus ( Westonia) ella 

 (Hall and Wliitfield) or Lingulella (Lingulejns) gregwa (Matthew) , reduced so that the surface, 

 under a strong magnifier, has a roughened or minutely papillose appearance. Matthew [1891, 

 p. 148] describes it as due to wavy squamose ridgelets having the edges and points directed 

 forward, as in Botsjordia pulclira (Matthew). Owing to tliis roughened surface the outer layer 

 of the shell usually adheres to the matrix, leaving the dark, shiny surface of the inner layer. 

 The inner surface is niarked by concentric rows of punctse and fine radiating striae. The 

 shell is of medium thickness and formed of a thin outer layer and several inner layers or lamellae, 

 wliich are more or less oblique to the outer layer on the anterior half of the shell, One of the 

 largest ventral valves has a length of 10 mm., width 8 mm.; a large dorsal valve has a length 

 of 9 mm., width 8 mm. 



The cardinal area and pedicle groove are usually obscured by the adhei'ing fragments of 

 shell. The pedicle groove is strong and narrows graduallj^ as it crosses the long area of the 

 ventral valve. The area of the dorsal valve is short and broad. 



The cast of the visceral cavity (v) is preserved in a number of specimens. In Plate XLV, 

 figures 1 and li, the heart-shaped pit (x), so characteristic of Oholus and of Lingulella acutangula 

 (Roemer), is clearly outlined. A narrow median septum (s) is found in the dorsal valve (PI. 

 XIjV, figs. Ij and 11), and the anterior lateral muscle scars (j, fig. li) are clearly shown in the 

 ventral valve. The centrals, middle laterals, and outside laterals can not be differentiated in 

 the trapezoidal area (c) in front of the heart-shaped pit. On the dorsal valve the centrals (h, 

 figs. Id, Ij, and 11) and anterior laterals (j, fig. Ij) are finely preserved. 



Considerable portions of the markings of the vascular system are preserved on the casts 

 of the interior of the valves. The main vascular trunks of the ventral valve are shown by 

 figures 1, la, and Ic, and the position of the parietal scar is also seen at ps (figs, la, Ic, and li). 



Observations. — Doctor Matthew sent me the types of this species for study and illustration. 



1 have not been able to interpret some of the interior markings in the manner that his figures 

 indicate, but this is not unexjDected when the obscure character of most of the specimens is 

 considered. Wlien at St. John, in 1877, 1 collected a large number of specimens of this species, 

 and, as they are somewhat better preserved than the types, drawings have been made of the 

 casts of the interiors of three ventral valves and one dorsal valve. 



The variety, spoken of by Matthew [1903, p. 204], from the lower portion of Division 2c 

 shows the outer surface unusually well preserved, but I do not think it is a distinct species 

 or worthy of a varietal name. In the collections made by Loper on McPhees Brook, Division 



2 of Matthew's section, there are small specimens that correspond to Matthew's variety asfera 

 collected on McNeil Brook; also adult specimens. The horizon is much lower, according to 

 Matthew's sections, but the specimens are very much alike from the two localities. 



Formation and locality. — Middle Cambrian: (301y) Shaly sandstones of Division C2c of Matthew, east side of 

 Courtney Bay, St. John; and (301x) sandstones of Division C2c of Matthew, in the city of St. John; both [Matthew, 

 1891, p. 148] in New Brunswick. 



(307c [Matthew, 1903, p. 205]) Sandstones probably belonging with Division C2c of Matthew, on Mira Riverj and 

 (307^) sandstone on McPhees Brook; both in eastern Cape Breton, Nova Scotia, Canada. 



62667°— VOL 51, PT 1—12 34 



