EEPORT ON THE BRACHIOPODA. 57 



qui est assez developde cliez les Megerlia, et beaucoup plus ehez les Terebratules. 

 L'appareil branchial resemble done &, celui du Platydia anomioides mais la bouche boucle 

 est moins large par rapport aux boucles laterales, les cirrlies des bras sont assez longs 

 et disposes par paires ou plutot cliaque cirrhe semble se divise, en deux filaments egaux. 

 Ce caractiere a dtd represents chez la Platydia anomioides par M. Davidson." 



After a lengthened examination of two specimens of this shell which I found adhering 

 to two examples of Waldheimia kerguelenensis dredged off Marion Island, neither Dr 

 Gwyn Jeffreys nor myself were able to detect any characters to distinguish them from 

 the well-known Mediterranean Platydia anomioides. Other smaller examples, dredged 

 by the Challenger Expedition off Prince Edward's Island, agreed exactly in shape and 

 size with some specimens dredged by Edward Forbes in the ^gean Sea. I have also 

 a specimen dredged by Mr W. S. Kent off the coast of Portugal near the Tagus, which 

 appears to be identical in shape with the two examples from the Marion Islands. 



The true Terehratella appressa of Forbes, or Platydia anomioides of Scacchi, from 

 the ^gean Sea, is generally more circular or orbicular; but among the specimens 

 dredged by my distinguished friend Edward Forbes, and given to me after his return 

 from the Mediterranean, are two or three examples that are transversely oval, and which 

 closely resemble larger specimens dredged by the Challenger Expedition. Owing to the 

 extreme shortness of the peduncle, the ventral valve is kept so close to the object to 

 which it is attached, that the asperities or irregularities of the rock or shell to which 

 it is attached are often reproduced upon it. This peculiarity is especially observable on 

 the smaller valve of Platydia davidsoni. 



As the name anomioides is now in general use, I do not feel inclined to disturb it, 

 although that of appressa, Forbes, seems to hold priority. The two species of Platydia 

 at present known are of small dimensions, none exceeding 7 mm. in length by 10 mm. 

 in breadth. The so-termed Morrisia gigantea, Deshayes, from off the Island of Bourbon, 

 is an example of Megerlia truncata. 



Argiop)e, E. Deslongchamps. 

 Argiope decollata, Gmel., sp. (PL IV. figs. 12, 13). 



Anomico decollata, Clieninitz, Conch. Cab., vol. viii. p. 96, pi. Ixxviii. fig. 705, and of the generality 



of modem authors. 

 Anomia detruncata, Gmelin, Syst. Nat. 

 Terebratula ungida, Retz., n. gen., Tert. 

 Terebratula aperta, Blainville, Die. Sci. Nat. 



Terebratula dimidiata, Scacchi = Terebratida Candida, Risso = Terebratula %irna<miiqva, Risso. 

 Megantheris decollata, D'Orb., and of DaU. 



Shell small, generally wider than long, semi-oval or obscurely sul:)pentagonal ; hinge- 

 line about as long as the greatest breadth of the shell. Dorsal valve semicircular, 



(ZOOL. CHALL. EXP. — PART I. 1880.) A 8 



