28 Transactions of thi Society. 



IV. — Notes on Shell-structure in the Genus Lingula, 

 Recent and Fossil. 



By Feedekick Chapman, A.L.S. F.K.M.S. 



(Palaeontologist to the National Museum, Melbourne.) 



(Bead November 19th, 1913.) 



Plate V. 



In a recently published paper on fossil (Silurian) species of Lingula, 

 one of which showed well-preserved shell-structure,* I commented 

 on the apparent discrepancies between Carpenter's and Gratiolet's 

 descriptions of shell-structure in this genus of Brachiopods, and 

 promised some further remarks on the question. By the courtesy 

 of Mr. C. J. Gabriel, who enabled me to examine microscopically 

 the shells of some recent Lingulse in his collection, I have studied 

 the minute structure of these shells by means of flakes and vertical 

 sections, and submit the results herewith as being of some scientific 

 interest. Two recent species of Lingula were examined, namely, 

 L. albida Hinds and L. anatina Lamarck. 



Carpenter s Description of Lingula Shell-structure. — This author 

 states f that "The structure of the shells of Lingula and Orlieula% 

 is equally peculiar, but very different from that which has been 

 now described. These shells are almost entirely composed of 

 laminae of horny matter, which are perforated by minute tubuli, 

 closely resembling those of ivory in size and arrangement, and 

 passing obliquely through the laminae. Near the margin of the 

 shell, these tubuli may be seen lying nearly parallel to the surface." 



In this description Dr. Carpenter did not say which species of 



* Proc. Roy. Soc. Victoria, n.s., xxiv. (1911) pt. 1, pp. 181-3, pi. xlv, figs. 3-5. 

 f On the Microscopic Structure of Shells. Rep. British Assoc. 1844 (1845) 

 p. 18. See pi. ix, fig. 22, of that paper. 



% Orbicula Sowerby, 1830 = Distinct Lamarck, 1819. 



EXPLANATION OP PLATE V. 



Pig. l. —Vertical section of shell of Lingula (Lilottidia) albida Hinds. Showing 



predominant corneous structure, x 150. 

 „ 2. — Vertical section of shell of L. anatina Lamarck. Showing predominance 



of calcitic layers, x 150. 

 n 3. — Vertical section of shell of fossil Lingula (L. lewisii Sowerby yar. 



flcmingtonensis Chapman) of Silurian age. Showing dark calcitic 



layers and fibrous corneous layers, x 190. 



