OBOLID^. 551 



I y LlNGULELLA CLiNGULEPIs) ACUMINATA SEQUENS Walcott. 

 Text figures 46A-B. 



Glossina acuminata Hall and Clakke [not Conrad], 1892, Eleventh Ann. Kept. State Geologist New York for 1891, 



PI. I, figs. 10 and 11. (No text reference.) 

 Lingula {Glossina) acuminata Hall and Clarke [not (Conrad)], 1892, Nat. Hist. New York, Paleontology, vol. 8, 



pt. 1, PI. I, figs. 1 and 2. (No text reference. Figs. 1 and 2 are copied from Hall and Clarke, 1892a, PL I, 



figs. 10 and 11, respectfully.) 

 Lingulella (Lingulepis) acuminatasequensWA-ijCOTT, 1908, Smithsonian Misc. Coll., vol. 53, No. 3, p. 72, PL VIII, fig. 4. 



(Characterized and discussed as a new variety. Fig. 4 is copied in this monograph as fig. 46A.) 



This variety differs from LinguleUa {Lingulepis) acuminata (Conrad) in being somewhat 

 less attenuate in its ventral valve, and in having the cardinal slope of the ventral valve straight, 

 instead of gently incurved. 



It occurs at a sKghtly higher geologic horizon than L. (L.) acuminata, and appears to be 

 a form, derived from that species. 



Judging from Hall and Clarke's illustrations [1892a, PI. I, figs. 10 and 11] they had rep- 

 resentatives of this variety of LinguleUa (Lingulepis) acuminata and mistook them for the 

 form illustrated by Hall [1847, p. 9] as Lingula acuminata. That figure represents a typical 

 form of L. (L.) acuminata, and is not the variety illustrated by 

 Hall and Clarke in 1892. 



The specimens illustrated by Hall and Clarke are given as 

 from Saratoga County, New York, "Calciferous sandstone." 

 The specimens wliich I have taken as typical of this variety 

 are from Division A of the Beekmantown limestone. 



This form owes its varietal name to the fact that it is a 

 later representative of the species. ^ B 



Figure 46.— LinguleUa (Lingulepis) acumi- 



Formation and locality. — Ordovician: (367c) Beekmantown limestone, nata sequens Walcott. A, Ventral valve 



Division A; quarry near the northwest suburb of Ticonderoga, Essex County, showing nearly straight lateral slopes 



New York ~ ^^' ®- ^'^*' '*^"^' *^^'- ^°- 53076a). B, 



^^ Dorsal valve (U. S. Nat. Mas. Cat. No. 



Lingulella (Lingulepis) eeos (Walcott). sssTsb). 



, ' The specimens represented are from Lo- 



Plate XXXIX, figures 9 and 9a. cality 367c near Ticonderoga, New York. 



Fig. 46A is copied from Walcott [1908d, PI. 

 Obolus (Lingulepis) eras Walcott, 1905, Proc. U. S. Nat. Mus., vol. 28, p. 333. vill, fig. 4]. it represents the type speci- 

 (Described and discussed as below as a new species.) men. 



Ventral valve elongate with rostral slopes gradually converging so as to form an acuminate 

 beak. Surface marked by fine concentric hues of growth and very fine, somewhat irregular, 

 concentric strise. Rather large scattered punctse occur on the interior surface. 



This species is represented by fragments and two broken ventral valves; these indicate a 

 length for the ventral valve of from 7 to 10 mm. It is alhed to LinguleUa (Lingulepis) acumi- 

 nata meeM ° (Walcott) of the Middle Cambrian fauna of the Teton mountains of Wyoming. 



Formation and locality. — Middle Cambrian: (C7) Lower limestone member of the Kiulung group [Black- 

 welder, 1907a, pp. 37 and 39 (last list of fossils), and fig. 8a (bed 33), p. 29], 2.2 miles (3.5 km.) southwest of Yenchuang, 

 Sintai district. Shantung, China. 



Linguella (Lingulepis) exigua (Matthew). 

 Plate XXXIII, figures 4, 4a; Plate XLIII, figures 1, la-z. 



Obolus (Lingulepis) gregwa Walcott (in part) [not (Matthew)], 1901, Proc. U. S. Nat. Mus., vol. 23, pp. 692-694. 

 (Described and discussed almost as on pp. 552-553, with the exception of the notes under "Observations," 

 which have been rewritten in this monograph. The following species were included in this reference: Lingu- 

 lella (Lingulepis) exigua, L. (i.) gregwa, Lingulella tumida, and L. atava.) 



a Written "week.ii" in the original description [Walcott, 1905a, p. 333] through mistake. 



