300 BRACHIOPODA. 



To give even a succinct statement of the conflicting views of 

 the authors first mentioned would unduly increase the number 

 of my pages ; those who wisli to pursue the subject further may 

 read with interest and profit : 



B. S. Morse. — American Journal of Science and Arts, p. 100, 



July, 1870. 

 Proc. Bost. Soc. Nat. Hist., xv, 1873. 

 Memoirs Bost. Soc. Nat. Hist., ii, 29, 1871. 

 Wm. H. Dall.— Am. Jour. Conchologv, vi, 88, 1871; vii, 39, 



1872. 

 A. Agassiz. — Review of Kowalevsky's Memoir, Am. Jour, of 



Science and Arts, 3d ser., viii, 470^ 1874 (Kowalevsky 



published in Russian). 

 F. Stoliczka. — Palseontologica Indica, vol. iv, Brachiopoda. 



Davidson's paper, "What is a Brachiopod ?" may also be con- 

 sulted by those desirous of reading a fuller account of the group 

 than is given in these pages. Greological Magazine (London), 

 for 1877 ; or a French translation in Annales de la Societe Mala- 

 cologique de Belgique, x, 1876. 



The Brachiopoda (= Order Palliobranchiata, Blainville, 1814) 

 are bivalve molluscoids, which differ from the ordinary mussels, 

 cockles, etc., in being alwa3^s equal-sided and never quite equi- 

 Jvalve. Their forms are sj'mmetrical, and so commonly resemble 

 antique lamps, that they were called lampades, or " lamp-shells," 

 by the old naturalists (Meuschen, 1787 ; Humphrej^s, 1797) ; the 

 hole which in a lamp admits the wick serves in the lamp-shell for 

 the passage of the pedicel by which it is attached to submarine 

 objects. 



The valves of the Brachiopoda are respectively dorsal and 

 ventral ; the ventral valve is usually largest, and has a promi- 

 nent beak, by which it is attached, or through which the organ 

 of adhesion passes. It is sometimes perforated, as in the Tere- 

 bratuiidffi. The dorsal or smaller valve is always free and 

 imperforate. The valves are articulated by two curved teeth, 

 developed from the margin of the ventral valve, and received by 

 sockets in the other ; this hinge is so complete that the valves 

 cannot be separated without injury. A few genera have no 

 hinge; in Crania and Discina the lower valve is flat, the upper 

 like a limpet ; the valves of Lingula are nearly equal, and have 

 been compared to a duck's bill. 



This and several other points of difference seem to show the 

 propriety of adopting the proposal made by Deshayes in 1836 of 



