72 Miscellaneous . 



it affords. But it is also possible that they may represent unfortu- 

 nate animals that had ages ago wandered into the dark recesses of the 

 cave, and in the total absence of light, and consequent disuse of their 

 visual organs, these organs may have become obliterated, or where 

 their forms remain, they may have become incapable of performing 

 their functions. In such an inquiry, the author remarked, that, like 

 the animals themselves, we grope in the dark. 



MISCELLANEOUS. 



On the Anatomy o/" Terebratula austrahs. By M. P. Gratiolet. 



1 . The muscles which move the shell. — The Brachiopoda are de- 

 stitute of the sort of spring which opens the shells of the Lamelli- 

 branchiate MoUusca. Cuvier in his work on Lingula supposed that 

 they separated the valves by means of their arms. Tliis explanation 

 has been adopted by Owen, Blainville, and Siebold. D'Orbigny has 

 put forward the opinion within the last few years, that the movement 

 which separates the valves might be explained by the action of the 

 corneous cilia with which the edges of the mantle are furnished. 



The author's examination of some specimens of Terebratula au- 

 stralis leads him to support the views announced by Quenstedt as 

 early as 1835, that the shell of these animals is opened by the action 

 of certain special muscles, which he calls diductors. These muscles 

 are attached to the cardinal process {taloii) of the imperforate valve 

 behind the point of articulation of the valves ; they raise this cardinal 

 process, and consequently depress the other extremity of the lever. 

 Thus there are mviscles to close the shell and others to open it. This 

 is peculiar to the Brachiopoda, and occurs in all the genera of which 

 the anatomy is known. 



[The true action of these muscles, called by Professor Owen Ad- 

 ductores breves, and by Mr. Davidson Cardinal muscles, is well 

 known in this country, having been pointed out by Mr. Woodward 

 in 1851. The question of the real nature of those processes of the 

 mantle which M. Gi-atiolet calls ' branchial papillae,' but which are 

 assuredly not branchial, will be found fully discussed by Dr. Car- 

 penter, " On the intimate structure of the Shells of the Brachiopoda," 

 Palseontographical Society, 1853.] 



Besides these muscles there are four symmetrical and very fleshy 

 muscles which pass from the valves to the peduncle. These muscles 

 cause the various movements of the shell upon its stalk. 



2. The mantle. — The structure of the mantle is remarkable. Its 

 edges are furnished with a crown of corneous cilia, finely annulated, 

 and originating in follicules, like true hairs. A circular muscle and 

 small radiating fibres move these ciliated margins. 



The internal lamina of the mantle is smooth and scarcelv vascular, 

 which is the reverse of what takes place in the Liny vice and Orbicidce ; 

 on the other hand, the outer lamina, is rich in vessels and covered 

 with branchial papillae which are inserted in the innumerable perfo- 



