180 Mr. L. Reeve on the History, Synonymy, and 



32. Terebratula [Bouchardia) fibula, Reeve, Conch. Icon. pi. 8. 

 f. 30 a, b. 



Hob. Bass's Strait, South Australia; Calvert. 



This remarkable shell is curiously intermediate in its characters 

 between T. {Bouchardia) Cumingii and tulipa. The beak is more 

 acuminated than in the former ; and the area of the deltidium, 

 which in B. Cumingii and tulipa is excavately grooved, is in B. 

 fibula flat. In respect of the callous development of the interior, 

 it is about intermediate between the other two. Mr. Calvert, of 

 whom the B. fibula was purchased for the British Museum, re- 

 ports that he dredged it in Bass's Strait from a depth of 200 

 fathoms; but Mr. Milligan, of Hobart Town, Secretary to the 

 Royal Society of Tasmania, now in London, informs me that 

 Bass's Strait, when sounded by Captain Stokes, was found not 

 to be deeper in any part than from 70 to 75 fathoms. 



33. Terebratula {Bouchardia) tulipa, De Blainville, Diet. Sci. 

 Nat. liii. f. 144. 



Bouchardia tulipa, Gray. 

 Terebratula rosea, Humphreys, ined. 

 Bouchardia rosea, Davidson. 

 Pachyrhynchus roseus, King. 

 Terebratula unguis, Kiister. 



Hab. Brazil (dredged at Rio Janeiro from a depth of about 

 10 to 13 fathoms) ; Macgillivray. 



T. [Bouchardia) Cumingii, fibula, and tulipa are distinguished 

 from all other Terebratula by the structure of the shell's beak, 

 which is acuminated and has the foramen at the extremity. The 

 deltidium plates are therefore dispensed with, and the length- 

 ened area which occupies their place is either flat, as \nB, fibula, 

 or excavately grooved, as in B. Cumingii and tulipa. Con- 

 comitant with this change in the structure of the beak there is a 

 change in the interior of the shell. The apophysial skeleton, 

 retaining the cross piece of Magas, becomes solidified and com- 

 paratively rudimentary, and callosities begin to be formed about 

 the hinge of B. Cumingii, until they assume in B. tulipa the 

 function of heavy interlocking plaits. 



Subgenus 7. Megerlia, King. 

 Apophysis a rather small loop on a pair of projecting blades 

 affixed by a laminated cross piece to a central septum, and on 

 either side by a short intermediate lobed process. 



34. Terebratula [Megerlia) truncata, Linn. Syst. Nat. p. 1152; 

 Conch. Icon. pi. 11. f. 48 a, b, c. 



Anomia truncata, Linnaeus. 

 disculus, Pallas. 



