224 DE. T. DAVIDSON ON RECENT BRACHIOPODA. 



concentric lines of growth ; texture horny, with a slight deposit of lime in the thickest 

 part of the shell, very finely perforated. Colour cream-white, with sometimes transverse 

 lines or bands of green, especially on its anterior half and edge. In the interior of the 

 ventral or longest valve two thin septa or ridges of small elevation diverge from the beak 

 to about one third of the length of the valve, and in the dorsal valve a single median 

 similar ridge or septum extends from under the beak to about one third of the length of 

 the valve ; muscular scars as in Glotlklia albida. The peduncle is very long, and secretes 

 a mucus to which grains of sand adhere, especially for some distance along its posterior 

 extremity. Length of shell 1 inch 1 line, breadth 6 lines. 



Mab. Island of Punam, Bay of Guayaquil, at about half-tide, on an extensive bottom of 

 hard coarse sand, at from four to six inches below the surface (Cuming and Broderip) ; 

 United States, New'berne to Port Royal ; coasts of North and South Carolina (Dall) ; Port 

 Wool (Brooks). Mr. Dall informs me by letter, 29 Jan., 1885, that he has received Glot- 

 tidla ivjramidata from Mr. Hemphill, South Plorida Keys, where the shell grows larger 

 and slightly thicker than the more northern specimens, but is otherwise identical, and 

 that it becomes attached when adult to beds of shell or pebbles. 



Ohs. An attentive comparison of many specimens of G. Audebarti, Broderip, and 

 G.pyramidata, Stimpson, has convinced me that they are the same species. Broderip's 

 name must consequently hold priority, and that of Stimpson be placed among the 

 synonyms. Glottidla Audeharti is w^ell distinguished by its shape from G. albida, Hinds. 

 In ' Science,' vol. iii. p. 325, 1884, Mr. W. H. Dall says that the Glottidia (?) antillarum. 

 Reeve, described from the West Indies, may be identical with it. 



Glottidia Audebartl varies a good deal in shape ; and Broderip * observes : — " The 

 rounded anterior edge of this shell is green, and tbe transverse lines of that colour are 

 produced by the progressive increase of the shell, which is smooth and parchment-like. 

 In all the dried specimens the thin anterior edge is contracted into a square form, so as 

 to produce a resemblance to a very square-toed shoe ; but in its natural state this edge is 

 rounded. A general contraction, moreover, gives the dried shells a narrower and more 

 ventricose character than they really possess ; and the remains of the cilia (setae) give to 

 their anterior edges a bearded appearance." 



The anatomy and embryology of this well-defined species have been studied with great 

 care by Professors Owen t, E- S. Morse %, and W. K. Brooks §. As it will not, 

 however, be possible in this monograph to reproduce all the important details they have 

 published upon the subject, we must limit ourselves to giving a few extracts from their 

 works, and refer the reader for more ample details to their respective memoirs upon 

 the subject. 



In an abstract of his paper on " The Brachiopoda, a Division of the Annelida " 



* Trans. Zool. Soc. vol. i. p. 144, 1S35. t Ibid. p. 157. 



X American Naturalist, vol. iv. 1870; Amer. Journ. Sei. >fe Arts, vol. 1., 1870; and Boston Soc. Nat. Hist, 

 vol. XV., 1873. 



§ Chesapeake Zool. Lab. Scientific Results, 1878. [Sec also licycr, " A Study of the Structure of Lhit/ida ( Glottidia) 

 pyramidata, Stimp., Dall." Studies Biol. Labor. Johns Hopkins University, Baltimore, vol. iii. no. 5, March 1886. — 

 A. C] 



