DE. T. DAVIDSOX OX EECEXT BEACIIIOPODA. 151 



tdtin (probably T. cordala of Risso) ; and I feel pretty confident that the last-named 

 species will be found on our own as well as the Mediterranean coasts." In 1859, Dr. S. P. 

 Woodward and myself spent a whole day at the British Museum in endeavouriii"-, with 

 tlie aid of a good microscope, to find some kind of calcareous support, or septum, l)ut could 

 tind none; nor has any other naturalist who has studied the shell been more successful. 

 In 1859, Prof. W. King proposed tlie generic name of Gwijnia for this form, statin"- at the 

 same time that "the principal generic character of Gwyuia is in the labial appenda"'es 

 being attached directly to the shell (first observed by Mr. Jeffreys), and not to a loop, as 

 in other genera of the family. The prominency of the umbonc of the small or receivin"- 

 valve, the form, position, and (considering the size of the species) the unusual develop, 

 ment of its teeth, also the large size of the perforations of its shell-tissue, form other 

 good distinguishing characters." We must, however, for the present, assume that no 

 calcareous support in reality exists. 



In a note published in the 'Ann. and Mag. Nat. Hist.' for Xov. 1880 (p. 400), Dr. Gwvn 

 Jeffreys again returns to the subject, in referring to what he terms Arcjiope capsula, and 

 says :— "The specimens kindly sent me by Mr.Duprey are larger than any I had previously 

 seen ; and I was enabled to examine the inside of the shell by soaking them for some 

 days in dilute potash water, together with Argiojye clstellula of the same size. A. can- 

 sula has a thick hinge ; and the smaller (though scarcely smaller) valve has a sharp-edo-ed 

 and wavy crest or ridge lying a little within the margin, which is heart-shaped and con- 

 tinuous in front. The shell is strong for its size, and is nearly spherical and cquivalve, the 

 beaks of both valves being excavated to contain the b^ ssus. There is no trace of a septum 

 in either valve. The caecal tubercles are numerous, twice as many as in ^. cislellula of 

 the same size. The latter species is transversely oblong ; there is a distinct and promi- 

 nent septum in each valve ; and the laminar ridge in the smaller valve is much sli<'hter 

 and is interrupted by the septum to which it is attached. Both species occur too-ether 

 on the English and Irish coasts, and at Etretat in Normandy." 



In his paper on the development of the skeleton in the genus Woldlieimia, Herman 

 Eriele says (p. 385), " Dr. Jeffreys has had the great kindness to send me his type-speci- 

 mens of Gwjjnia {Arfi'iope) copsiila, Jcffr., for comparison. My first glance at them sufficed 

 to convince me that there can be no question as to their [not *] being the fry of Wcddheimia 

 cranium, for not only are both valves of very nearly the same size, but the form, the 

 foramen, and the structi.u*e of the shell are essentially different." 



Mr. Lovell Beeve writes, in his ' Geographical Distribution of the Terebratula; ' f , " Is 

 this very minute form, it has been asked, an adult shell, or the fry oi Arrjiope cistcllulum 

 or of some other Tevcbmtvla ? An Argiope it certainly is not ; and I am unable, after a 

 most tedious examination of specimens, to add anything to what is knoAvn on the subject." 

 The question being still involved in considerable uncertainty, it will be better, I 

 think, at any rate provisionally, to leave it under Gwrjnia, from which it may be 

 hereafter removed, if anything definite should be ascertained concerning it. 



* [Hcrr Friclo writes Ai)ril lOtli, ISSO, tliat " by a printer's error the -svord ' not " was omitted here : " and Ihis 

 is evident from the rest of the passage quoted. — A. C] 

 t Ann. & ilajr. Nat. Hist. 3rd scr. vol vii. p. 1,^3. 



