18 BULLETIN OF THE 



Subfamily PLATIDIIN^E. 

 Platidiinm Dall, Am. Journ. Conch., VI, p. 142, 1870, 



Genus PLATIDIA Costa. 



Platidia 0. G. Costa, Faun, del Reg. Napoli, p. 47, January, 1852. — Dall, 

 Am. Journ. Conch., VI, p. 142, 1870. 



Morrisia Davidson, An. Mag. Nat. Hist., p. 371, May, 1852, and the gener- 

 ality of authors. 



Platidia anomioides Scacchi sp. 

 Terebratula anomioides Scacchi ; Phil. Moll. Sicil., II, p. 69, pi. xviii, fig. 



9, 1844. 

 Platidia anomioides Costa, 1. c. ; Dall, Am. Journ. Conch., VI, p. 143, figs. 



20, 21, 1870. 



This species was dredged off the Samboes on the Florida coast in two 

 hundred and thirty-seven fathoms. This is the second genus (Crania being 

 the other) of Brachiopoda which has been added to our fauna by the 

 researches of the United States Coast Survey Expedition. It has since 

 been obtained by Mr. J. Gwyn Jeffreys, F. R. S., of the English Deep-Sea 

 Dredging Expedition on the Porcupine, in 1869, in the Shetland Channel, 

 at a depth of three' hundred and forty-five fathoms. Previously this species 

 had only been known as an inhabitant of the Mediterranean in deep water. 

 The specimen from the Florida coast presents no differences in size or 

 general appearance from the Mediterranean form. The calcareous prisms 

 of which the shell is composed, and the perforations, are remarkably large 

 and conspicuous. 



Subfamily MEGATHYRINyE Dall. 



Megathyrinaz Dall, Am. Journ. Conch., VI, p. 143, 1870. 

 Argiopidcv King, Perm. Foss., p. 142, 1850. 



Shell with a straight wide hinge line ; apophyses consisting of a sub- 

 marginal loop, attached to the hinge margin, provided with crura and 

 intersected by one or more submarginal elevations or septa. 



Brachia in a single series, following the loop, surrounding a smooth disk 

 or membrane, in the posterior median portion of which the mouth is 

 situated. Setae absent from the mantle edge. Pedunculated. 



Genus MEGATHYRIS D'Orb. 



Megathyris D'Orbigny, Pal. Fran. Ter. Cret., p. 147, 1847. — Dall, Am. 



Journ. Conch., VI, p. 144, 1870. 

 Argiope Deslongchamps, Mem. Soc. Lin. Norm., VII, p. 9, 1842. 

 Not Argiope Savigny, Desc. de l'F^gypte, XXII, p. 334, 1827. — Thorell, 



Ann. Mag. Nat. Hist., p. 190, 1868; a genus of spiders. 



