532 CAMBRIAN BRACHIOPODA. 



proves to be a true Lingulella. In the same piece of rock an obscure form of Oholus occurs 

 that may be a medium-sized Oholus apollinis Eichwald. I take pleasure in naming the Lin- 

 gulella after its discoverer, Dr. J. S. Siemiradzki. 



Formation and locality. — Middle Cambrian: (368) Quartzitic sandstone in tlie Pepper Mountains, near 

 Sandomierz, on the Vistula, Russian Poland. 



Lingulella ? signata (Barrande). 

 Plate XXX, figure 11. 



Lingula ? signata Barrande, 1868, Faune silurienne des environs de Hof, en Bavifere, p. 103, fig. 73. (Described 

 and discussed in French as a new species. Fig. 73 is reproduced in this monograph, PL XXX, fig. 11.) 



Lingula f signata Barrande, 1868, Neues Jahrb. fiir Mineralogie for 1868, p. 692, unnumbered plate, fig. 73. (Copy 

 of preceding reference.) 



This species is doubtfully referred to Lingula by its author. It is oval in outline, with 

 a strongly arched surface. Where the shell is partly removed two small, elongate impres- 

 sions are seen near what is supposed to be the posterior portion of the valve, and on the front 

 portion of the shell a longitudinal groove. Barrande [1868a, p. 103] remarks that the latter 

 recalls the perforation of Discina; but it is not perforated, as the shell continues over the 

 entire surface of the depression. The aspect of the shell is homy and without ornamentation. 

 Length, 2.5 mm.; width, 2 mm. 



It is very doubtful if this species should be refeiTed to Lingulella, but it may possibly 

 be a rounded dorsal valve somewhat like that of L. mosia (Hall), L. ferruginea Salter, or Lingu- 

 lella (Lingulepis) acuminata (Conrad). 



Formation and locality. — Passage beds between the Upper Cambrian and the Ordovician: (303c [Barrande, 

 1868a, p. 103]) Suburbs of Hof, Bavaria, Germany. 



Lingulella similis (Walcott). 



u 



Plate XXI, figures 2, 2a-j, 3, 3a-d. 



Oholus (Idngulella) similis Walcott, 1898, Proc. U. S. Nat. Mus., vol. 21, pp. 41.5-416. (Described and discussed 

 as below as a new species.) 



Shell small, general form ovate, with the ventral valve subacuminate, and the dorsal 

 valve rounded ovate in outline. There is some variation m the outline of the valves; this 

 may be seen by comparing Plate XXI, figxires 2 and 2b, of the ventral valve, and figures 2a 

 and 2c of the dorsal valve. Surface of the shell marked by concentric lines of growth and 

 very fine, slightly irregular, concentric striae. Where the outer surface is well preserved, fine 

 radiating striae may be seen with a strong magnifying glass. When the outer layer of the 

 shell is exfohated the outer surface of the inner layer is marked by fine concentric lines and 

 very fine numerous radiating striae; the inner surface of the shell shows concentric lines of 

 growth and faint, scattered pits or punctse. The shell is of medium thiclaiess and formed 

 of a thin outer layer, with one or more inner layers or lamellae. The latter are especially prom- 

 inent toward the front, where they have essentially the same arrangement as in Lingulella 

 acutangula (Roemer). The average length of the ventral valve is from 4 to 5 mm.; width, 

 2.5 mm. An associated dorsal valve 4 mm. m length has a width of 3 mm. 



A cast of the interior of a ventral valve shows a clearly defined area of medium length. 

 It is divided midway by a cast of a narrow, strong pedicle furrow, and on each side by fiexure 

 lines situated about two-thirds the distance from the pedicle furrow to the lateral margin; 

 a few indistinct strias cross the area parallel with its base. The area of the dorsal valve as 

 seen in a cast is well defuied and rather large; it is marked by fine, transverse striae of growth 

 and indistinct flexure lines. A cast of the interior of the dorsal valve shows a trace of the 

 visceral cavity and a narrow median septum. The only muscle scars observed are the two 

 umbonal scars in the ventral valve (g), figure 2, and the central (h) and the anterior lateral 

 scars (j) of the dorsal valve, figure 2a. 



