OBOLID^. 531 



The outer surface of the inner layers shows radiating strias and concentric lines of growth. 

 The radiating striae are also present on the inner surface outside of the area of the vascular 

 cavity. 



The shell is thick and formed of a thin outer layer and several thin inner laj^ers or lameUse 

 arranged very much as in other shells of the genus lAngulella. The largest ventral valve has 

 a length of about 11 mm.; Avidth, 7 mm. A dorsal valve 8 mm. in length has a width of 

 5.5 mm. 



Casts of the interior of the ventral valve show a well-marked area, with a broad, strong 

 pedicle furrow. The base of the area arches stronglj^ forward. Just at the center, across the 

 pedicle furrow, however, it has a slight backward arch. None of the specimens show the 

 flexure line or the extent of the area along the cardinal slopes of the valve. The area of the 

 dorsal valve is unfaiown. None of the characters of the visceral cavity or vascular marldngs 

 are shown with sufficient clearness to describe them. A tubercle on each side of the median 

 line, just in advance of the area, indicates the main vascular sinus, and a depression tlie position 

 of the anterior portion of the visceral cavity. 



Observations. — This is probably the oldest species of the genus Lingulella. It is associated 

 with Botsfordia cselata (Hall), ElliptocepJiala asapTioides Emmons, and other characteristic 

 species of the Lower Cambrian. In its elongate dorsal valve it recalls Obolus rhea Walcott 

 of the Middle Cambrian (PL IX, figs. 1, la-c). It differs from that species in the character of 

 the shell and the outline of the valve. 



The specific name is given in honor of Prof. Charles Schuchert, who collected the only speci- 

 men of the species known to me. 



Formation and locality. — lower Cambrian: (367) Conglomerate and limestone, Troy, Rensselaer County, 

 New York. 



Lingulella siemiradzkii (Walcott), 

 Plate XXXI, figm-es 2, 2a. 



Lingula sp. cf. exunguis Eichwald, Siemiradzki, 1886, Jahrb. K.-k. geol. Reichsanstalt for 1886, Bd. 36, Hft. 4, 



p. 672. (Mentioned in German.) 

 Lingula cf. exunguis Eichwald, Gukich, 1892, Neues Jahrb. filr Mineralogie, Bd. 1, p. 69. (Mentioned in German.) 

 Lingula sp. Lingula aff. exungui Eichwald, Gurich, 1896, Verhandl. Russ.-kais. min. Gesell. St. Petersburg, 2d ser., 



Bd. .32, p. 214. (Discussed.) 

 Obolus {Lingulella) sieiniradzkii Walcott, 1901, Proc. U. S. Nat. Mus., vol. 23, pp. 690-691. (Discussed as below 



as a new species.) 



Attention was called to this species by Siemiradzki [1886, p. 672] in connection with his 

 study of the Paleozoic rocks of the Mittelgebirge of Poland. He speaks of it as "Lingula sp." 

 in the black conglomerate, and compares it with " L. exunguis Eichwald." In the associated 

 gray sandstone he fornid an Oiolus which he says is identical with "0. siluricus Eichwald." 



Gurich discusses the Cambrian of Sandomierz in a paper on the Paleozoic of the Mittel- 

 gebirge, and mentions [1896, p. 17] Siemiradzki's discovery of fossils in the lower sandstones 

 and shales. 



Giirich added greatly to the fauna found by Doctor Siemiradzki. He mentions [1896, 

 p. 17] Paradoxides cf. tessini, P. hohemicus, Agnostus fallax, A. gihius, and Liostracus linnars- 

 soni, and refers the fauna to the Middle Cambrian. The "Lingula" he compares [1896, p. 214] 

 with "Lingula crassa Eichwald," calling attention to the resemblance in the surface charac- 

 ters; also to those of Lingulella davisi (McCoy). 



This is a small shell belonging to the group of species containing Lingulella ferruginea 

 Salter, L. des'lderata (Walcott), etc. The outer surface is marked by concentric, slightly undu- 

 lating, and imbricating striae of growth, and the outer surface of the inner layers by fuie radiat- 

 ing striee. The general form and other characters are represented in Plate XXXI, figures 2 

 and 2a. 



Through the kindness of Dr. Fr. Schmidt I received a fragment of gray quartzitic sand- 

 stone containing a large number of specimens of the "Lingula" of Siemiradzki. The shell 



