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Journal of Paleontology 91(6):1123–1147
as wide as long (instead of elongate, as in H. umbonata), less inflated, and with a more pronounced anterior fold. In eastern Anticosti, this is the stratigraphically lowest species of Hindella, occurring directly above sandstones of the Velleda Member of the Vaureal Formation. The elongate shells of Hindella umbonata occur upstream on the Prinsta River at locality A813 (see localities of H. umbonata). Hindella prinstana is abundant in the Prinsta and Fraise members at both ends of the island. Shaler (1865) reported his species “Athyris turgida” from
“1/2 mile north of White Cliff”, which posits it within the Fraise Member, and is thus a probable synonym of H. prinstana. The specimen illustrated by Sheehan (1977) resembles
those from the lower recessive shales of the Fraise Member at Junction Cliff, and is thus assignable to H. prinstana.
Hindella bulbusa new species Figures 2.8–2.13, 3.1–3.17, 4
Types.—Holotype, GSC 137671 (Fig. 3.1–3.5); figured para- types, GSC 131790, 137670, 137679–137681 (Figs. 2, 3), and 131799 (serially sectioned specimen; Fig. 4). Parastrophinella Bluff, southwest coast of Anticosti Island, locality A84 (=C720; see Jin and Copper, 1997). First coastal bluff scree outcrops ~700 m southeast of Junction cliff (UTM 20, 0397126E, 5518771N). Lower half of bluffs of thinly bedded micrites, shales with abundant Parastrophinella reversa in several layers (type locality), and a diverse benthic fauna (see Jin and Copper, 2008, fig. 6C). Upper Parastro Member, Ellis Bay Formation, middle Hirnantian.
Diagnosis.—Relatively small, elongate, suboval shells of Hindella, with narrow apical angle and low beak; usually prominent growth disruptions, concentric filae, and more distinctive radial capillae; gentle fold and sulcus developed towards anterior commissure. Dental plates straight, flanking wide lateral cavities; small teeth; 7 or 8 spiral whorls; simple low jugum and flat jugal arch.
Description.—Shells relatively small, longer than wide, bulbous, ovoid to pear-shaped, wider anteriorly than posteriorly. Apical angle relatively narrow, rounded. Adult shells 8–10mm wide (average = 10mm), with average thickness of ~9mm. Umbo strongly convex, inflated. Anterior commissure weakly plicate. Internal structures as in diagnosis.
Etymology.—From the Latin, bulbus, a swell, referring to the globular, pear-shaped shell typical of the new species.
Remarks.—The new species is readily distinguished from Hindella umbonata (Billings, 1862) and H. prinstana (Billings, 1862) of the underlying Juncliff and Fraise members by its smaller size (with average width 10mm versus 16mm for H. umbonata, and average thickness 9mmversus 12mmfor the large shells of H. umbonata), slightly wider apical angle, more bulbous shape, and less robust shell wall. Hindella umbonata is strongly elongate, with parallel sides, whereas H. bulbusa n. sp. reaches its maximum width anteriorly, giving it a pear shape. The umbo of H. bulbusa n. sp. is relatively pinched, given its narrow apical angle of ~110°, versus 100° in H. umbonata.
Hindella bulbusa n. sp. is common only at the western (e.g., Parastrophinella Bluff) and middle parts of Anticosti Island, and appears to be absent at the east coast.
Genus Cryptothyrella Cooper, 1942
Type species.—Whitfieldella quadrangularis Foerste, 1906. Brassfield Formation, Aeronian, Dunkinsville (=“Duncans- ville” of Foerste, 1906), Adams County, Ohio.
Species assigned.—In addition to the type species, the following species are assignable to Cryptothyrella: Atrypa crassa Sowerby, 1839.—Goleugoed Formation,
late Rhuddanian, Girvan. Terebratula furcata Sowerby, 1839.—Bog Quartzite,
Aeronian, Shropshire. Atrypa cylindrica Hall, 1852, p. 76, pl. 24, figs 2a–h.—Iron- deqoit Formation, basal Sheinwoodian, Niagara region, New York
(strongly elongated shell with prominent capillae). The shells figured later as “Whitdieldella cylindrica Hall” by Hall and Clarke (1894, pl. 40, figs. 16–22) are from the “Niagara group” (=Bisher Formation, coeval with the Irondequoit Formation; C.E. Brett, personal communication, 2017), “Hillsboro, Ohio” and have anterior plicae and capillae. Cryptothyrella bisulcata Gauri and Boucot, 1970.—Brass- field Limestone, Aeronian, near West Union, Ohio.
Species questionably assigned.—The following species require further study to establish their generic affinities: Hemithyris angustifrons M’Coy, 1851.—Mulloch Hill
Formation, late Rhuddanian, Girvan. Internal structures poorly known. Whitfieldella subquadrata Foerste 1906, p. 326, pl. 1,
figs. 3a–f.—Indian Fields Formation, Aeronian, Berea, Kentucky. Regarded as junior synonym of the type species Cryptothyrella quadrangularis by Gauri and Boucot, 1970.
Diagnosis.—Shell medium to relatively large, elongate, globose, smooth to capillate, uniformly biconvex to bisulcate. Very small deltidial plates flanking transapical foramen in adult
shells; beak incurved. Ventral umbo thickened internally by callus fill, leaving narrow medial groove; teeth small, rounded; dental plates short,with thin terminations,medially inclined, fused posteriorly through prismatic thickening, becoming discrete anteriorly; dental cavities mostly infilled with prismatic callus posteriorly. Socket plates relatively thin, but inflated apically to support dental sockets; crura thin, delicate, parallel to each other, extending along commissural plane. Umbonal blades terminated as hooks, fused to crura; jugal saddle almost flat, positioned in mid-shell; spiralia with 8–10 whorls, directed laterally.
Remarks.—Based on Gauri and Boucot’s (1970) study of Cryptothyrella, Ziegler and Boucot (1970) proposed a Cryptothyrella community for North America. The genus, however, has had a shifting taxonomic history between a valid genus Cryptothyrella to a synonym of Hindella, resulting in a confusing stratigraphic range between the Late Ordovician (Hirnantian) and early Silurian. Various species have been
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