BRACHIOPODA. 
205 
Conrad.* The former has a very considerable range, appearing, according to 
Davidson| in the Caradoc, Lower and Upper Llandovery, Woolhope, Wenlock 
and Ludlow formations. 
In America it has been found only in the Niagara group, while its congener, 
Orthis varica, Conrad, a very distinct species,! is confined to the Lower Helder- 
berg fauna. 
DALMANELLA 
(nom, propos). 
X. Group of Orthis testudinaria, Dalman. 
PLATE Vb, FIGS. 25-39; and PLATE Vc, FIGS. 1-47. 
1828. Orthis, Dalman. Kongl. Vet. Acad. Handl., pp. 115, 117, pi. ii, fig. 4. 
1842. Orthis, Emmons. Geology of N. Y. ; Rept. Second Dist., p. 404, fig. 4. 
1842. Orthis, Vanuxem. Geology of N. Y. ; Rept. Third Dist., p. 139, fig. 4. 
1843. Orthis, Atrypa? Hall. Geology of N. Y.; Rept. Fourth Dist., p. 105, fig. 6; p. 175, fig. 4, and 
p. 271, fig. 4. 
1843. Orthis, Conrad. Proc. Acad. Nat. Sci., Phila., vol. i, p. 133. 
1847. Orthis, Hall. Palaeontology ofN. Y., vol. i, pp. 117, 118, 120, 128, pi. xxxii, figs. 1, 2, 5, and pi. 
lxxix, fig. 4. 
1852. Orthis, Hall. Palaeontology of N. Y., vol. ii, p. 152, pi. lii, fig. 3. 
1856. Orthis, Billings. Canadian Nat. and Geol., vol. i, p. 40, fig. 1, and p. 136, pi. 2, fig. 5. 
1857. Orthis, Billings. Rept. of Progress Geol. Surv. Canada for 1856, p. 296. 
1857. Orthis, Hall. Tenth Rept. N. Y. State Cab. Nat. Hist., p. 42, figs. 1, 2, and p. 44, fig. 1. 
1859. Orthis, Hall. Palaeontology of N. Y., vol. iii, pp. 168-172, pi. xii, figs. 1-21, and pi. xiii, figs. 1-12. 
1859. Orthis, Billings. Canadian Nat. and Geol., vol. iv, p. 434, fig. 10. 
1860. Orthis, F. Roembr. Sil. Fauna westl. Tennessee, p. 62, pi. v, fig. 7. 
1860. Orthis, Hall. Thirteenth Rept. N. Y. State Cab. Nat. Hist., p. 121. 
1862. Orthis, Hall. Geology of Wisconsin, vol. i, p. 42, fig. 7 and p. 436. 
1862. Orthis, Billings. Palaeozoic Fossils, vol. i, p. 79, fig. 72. 
1862. Orthis, Hall. Fifteenth Rept. N. Y. State Cab. Nat. Hist., pi. ii, figs. 1-3. 
1863. Oi'this, Billings. Geology of Canada, pp. 130, 165, 231, 312, figs. 57, 144, 246, 320. 
1867. Orthis, Hall. Palaeontology of N. Y., vol. iv, p. 35, 46, 62, pi. v, figs. 1, 2; pi. vi, fig. 1 and 
pi. viii, figs. 3-8. 
1868. Orthis, Meek and Worthkn. Geology of Illinois, vol. iii, p. 373, pi. vii, fig. 6. 
1873. Orthis, Meek. Palaeontology of Ohio, vol. i, pp. 103, 109,. 112, pi. viii, figs. 1-3, 5. 
1874. Orthis, James. Cincinnati Quart. Jour. Sci., vol. i, p. 19. 
1875. Orthis, Miller. Cincinnati Quart. Jour. Sci., vol. ii, pp. 20, 22, 24, 30. 
* The Orthis acutiloba of Ringceberg is a form of O. biloba in which the lobes are very divergent. All 
stages of variation between this extreme and the normal form for the species are readily detected in any 
large collection. 
t British Silurian Brachiopoda, p. 208. 
J Davidson (Silurian Brachiopoda, p. 207) and Quenstedt (Petrefactenkunde Deutschlands, pi. Iv, figs. 
67-70), erroneously regarded this species as indentical with O. biloba. 
