646 CAMBRIAN BRACHIOPODA. 



AcROTHELE INTERMEDIA Liiinarsson. 

 Plate LVI, figures 3, 3a-d. 



AcToihele intermedia Linnaksson, 1879, Sveriges Geol. Undersokning, Afhandl. och Uppsatser, Ser. C, No. 35, pp. 



25-27, PL III, figs. 40-44. (Described in Latin, and described and discussed in Swedish, as a new species. 



Figs. 40-44 are reproduced in this monograph, PI. LVI, figs. 3, 3a-d, respectively.) 

 Acrothele intermedia Linnarsson, Gronwall, 1902, Danmarks geol. Unders^gelse, Rsekke 2, No. 13, p. 39. (Localities 



mentioned in Norwegian.) 



A comparison of the figures of Acrothele intermedia on Plate LVI, with those representing 

 A. coriacea Linnarsson and A. {Eedlichella) granulata (Linnarsson) on the same plate, shows 

 very clearly that A. intermedia is related in form to both, but that it differs in narrowing pro- 

 portionately more toward the posterior margin. Linnarsson [1879, p. 26] states that in surface 

 characters it agrees more nearly with A. coriacea. The outer surface is described as having 

 numerous fine concentric striae without granules. He gives [1879, p. 26] the dimensions of two 

 ventral valves as "length 8 and 6 mm., width 9.5 and 7 mm., respectively." A dorsal valve 

 9 mm. in length has a width of 11 mm. 



I have not seen the tj^pe of this species, or found specimens of it in the collections received 

 from Sweden. Five of Linnarsson's figures are reproduced on Plate LVI. Two of these show 

 a somewhat different position and arrangement of the main vascular canals and branches of 

 the ventral valve than in A. coriacea Linnarsson. 



Formation and locality. — Middle Cambrian: (16h) Limestones of the Paradoxides fonhhammeri zone at Borre- 

 gaard; and (334a [Gronwall, 1902, p. 39]) limestones of the Conocoryphe exsulans zone at BoiTegaard; both on Born- 

 holm Island, Denmark. 



(320]i) Shales in the Paradoxides tessini zone at Lovened, Province of Skaraborg; (320i) limestones of the Coronatus 

 zone, at Andrarum, 20 miles (32 km.) noilhwest of Simrishamn, Province of Christianstad ; (320j) limestones of the Coro- 

 natus zone, at Gislof, Province of Malmohus; and (320k) limestones of the Coronatus zone, at Kivihs Esperod, Province of 

 Malmohus; all [Gronwall, 1902, p. 39] in Sweden. 



(320q) Limestone forming 2c of the Paradoxides forchham.meri zone at Alunbruk (alum works), southern part of 

 Oeland Island, Sweden. 



Specimens that are rather doubtfully compared with Acrothele intermedia occur at the fol- 

 lowing locality : 



Upper Cambrian: (304j [Mason College Coll.]) Lower Stockingford shales, Puxley Park Lane, halfway up the 

 path to the quarry, Atherstone, Warwickshire, England. 



Acrothele levisensis Walcott. 



V/" Plate LXXXI, figures 12, 12a-b. 



Acrothele levisensis Walcott, 1908, Smithsonian Misc. Coll., vol. 53, No. 3, p. 85, PI. VIII, fig. 13. (Described and 

 discussed as below as a new species. Fig. 13 is copied in this monograph, PI. LXXXI, fig. 12.) 



Outline transversely broad ovate, ventral valve moderately convex at the apex, which 

 is about the posterior fifth of the length of the valve; pedicle aperture small and situated on 

 the slope back of and near the apex. Dorsal valve depressed convex, with a very gentle slope 

 from the umbo to the front margin and a greater slope to the marginal beak. 



Surface marked by fine concentric lines and striae that cross the space back of the apex 

 without apparent interruption. A compressed ventral valve 8 mm. in length has a width 

 of 10 mm. A dorsal valve has a length of 7 mm.; width, 8 mm. 



The cast of the interior of a compressed dorsal valve shows a median ridge that expands 

 near the center of the valve, and a main vascular sinus on each side that has the same general 

 course as in Acrothele coriacea Linnarsson. 



Observations. — In general form this species is much hke Acrothele coriacea and related 

 species. It differs from them in having a smooth surface except for the concentric lines and 

 striae. 



The four specimens representing this species were attached to a block in the collections 

 of the Geological Survey of Canada, with specimens of ETkania desiderata (Billings). 



The specific name is derived from Point Levis, the type locality. 

 Formation and locality. — Lower Ordovician: (319a [Geol. Survey Canada]) Levis shale, Point Levis, Province 

 of Quebec, Canada. 



