BRACHIOPODA. 
315 
Thecidea and Pterophloios. If this be true, they constitute the only satisfac¬ 
torily known representatives of the family Thecideid^ in palaeozoic faunas. 
Kayser described, unier the name Leptodus Richthofeni, a species of Lyttonia 
from among the fossils collected by Richthofen in China; otherwise these 
genera are unknown outside of India, 
Genus RICHTHOFENIA, Kayser. 1881. 
1863. Anomia, de Koninck. Quartei’ly Journal Geol. Soc. London, vol. xix, p. 6, pi. iv, figs. 7-9. 
1863. Anomia, de Koninck. Foss. Paleoz. de I’Inde, p. 18, pi. iii, tigs. 7-9. 
1881. RicMTiofenia, Kayser. Zeitschr. der deutsch. geolog. Gesellsch., vol. xxxiii, p. 351. 
1882. Anomia {RicMTiofenia), Waagen. Neues Jahrb. filr Mineral., vol. i, p. 116. 
1883. Richtliofenia, Waagen. Records Geol. Survey of India, vol. xvi, pt. i, p. 12, pis. i, ii. 
1883. RicTithofenia, Kayser. Richthofen’s China, vol. iv, p. 195, pi. xxiv, figs. 6-8. 
1885. RicTithofenia, Waagen. Productus-limestone Fossils; Brachiopoda, pp. 733-743, pi. Ixxxii, 
fig. 1; pi. Ixxxii A, figs. 1-4 ; pi. Ixxxiii, figs. 1-19. 
These peculiar fossils, which bear a striking external resemblance to certain 
operculated corals, and present some suggestive similarities to the lamellibranchs 
Fig. 248. 
Fig. 249. 
Fig. 250. 
Fig. 251. 
Richthofenia Lawrenciana, de Koninck. 
Pig. 248. The exterior of the two valves in articulation. 
Fig. 249. Longitudinal section of the pedicle-valve; showing the interior cavity and the cellular shell substance. 
Fig. 250. The interior of the pedicle-valve; showing the hinge-line and muscular scars. ^ 
Fig- 251. The interior of the brachial valve. (Waagen.) 
