204 DE. T. DAVIDSON OX KECE^^T BEACHIOPODA. 



TJncei'tain Species. 

 112. DisciNiscA (?) ANTILLARUM, d'Orbigiiy. (Plate XXVI. figs. 31-31 a.) 



Orbicula antillarum, d'Orbigny, Moll, cle Tlsle de Cuba dans le voyage ;\ Cuba de Ramon de la Sagra, 

 p. 368, pi. 28. figs. 34-36, 1853. 



Discina antillarum, E. Suess, Ueber die Wohnsitze der Brachiopoden, SitzuBgsb. k. Akad. Wissensch. 

 Wien, Bd. xxxvii. p. 228, 1859. 



Orbicula antillarum ?, L. Beeve, Conch. Icon., JMonogr. of Orbicula, pi. i. fig. 2, 1862. 



Discinisca? antillarum, Dall, Report on the Bracli. obtained by the United States Coast-Survey Exp., 

 Bull. Mus. Comp. Zool. Harvard, vol. iii. p. 42, 1871, and Proc. Acad. Nat. Sci. Philadelphia, p. 177, 

 July 1873. 



Shell small, circular. Larger or upper valve limpet-like ; apex subcentral ; one third 

 of the valve from the apex is smooth, the remainder radiately striated. LoAver valve not 

 known. Shell-structure horny and calcareous. Colour light yellowish brown. Length 

 and breadth 2 lines. 



Bah. Cuba, Martinique (d'Orbigny & Cuming). 



Ohs. I have never seen a real type of this very small species (or young stage of some 

 other ?). D'Orbigny says, " Cette espece n'a que les bords marques de stries rayonnantes, 

 le reste est lisse; elle est mince, fragile, transparente et pourvue de lougcils tout autour. 

 Nous I'avons rencontree fixee sur un madrepore proveuant de I'ile de Cuba." 



In his monograph on Orbicula Mr. L. Eeeve observes that " Mr. Cuming possesses 

 specimens of 0. antillarum, both from Cul)a and Martinique, in all of which the vertex 

 is inclined more posteriorly, while the shell is less regularly striated and less cancellated 

 than in the Eastern 0. stella ; but the shells are wonderfully alike in general aspect." 

 The specific claims of this so-termed species will require confirmation by the inspection 

 of additional Cuban specimens. 



113. Discinisca stella, Gould. (Plate XXVI. figs. 27-30.) 



Discina stella, Gould, ]\Iem. Boston Soc. Nat. Hist. vol. vii. p. 323 ; Otia Conch, p. 120, 1860. 



Orbicula stella, L. Reeve, Conch. Icon., Monogr. of Orbicula, pi. i. fig. 1, 1862. 



Discina stella, A. Adams, Ann. & ilag. Nat. Hist. 3rd ser. vol. ii. p. 100, 1863; Dall, Amer. Journal 

 of Conch, vol. vii. part 2, p. 76, 1871. 



Discinisca stella, Dall, Report on the Brachiopoda obtained hy the United States Coast-Survey Exp. 

 in charge of L. F. de Pourtales, Bull. Mus. Comp. Zoul. Harvard, vol. iii. p. 41, 1871, and Proc. Acad. 

 Nat. Sci. Philadelphia, p. 201, 1873. 



Discina stella, Davidson, Proc. Zool. Soc. April 1871, p. 311, pi. xxx. fig. 5, and Report on the 

 Brachiopoda of the Voyage of H. M.S. 'Challenger,' Zoology, vol. i. p. 64,1880; G. Dunker, Index 

 Moll, maris Japonici, p. 254, 1882. 



Shell orbicular, about as broad as long. Upper valve conical and moderately elevated ; 

 vertex subcentral. Surface marked by numerous radiating striaj ; vertex alniost smooth 

 The attached or lower valve is remarkably thin, almost fiat or slightly concave, and 

 sometimes does not seem quite to reach the edge of the upper valve ; in the posterior 

 half of the valve a wide heart-shaped disk exists, with an elongated oval-shaped slit or 

 foramen for the passage of the peduncle. From the margins of this disk radiate fine 



