BRITISH SILURIAN BRACHIOPODA. 93 



Professor Hall devotes several pages of the ' Sixteenth Report of the Regents of the 

 University of the State of New York ' (1863) to the genus Befzia and to his genus 

 Rhynchospira, 



Betzia Salteri and B. Bouchardi have been referred by Professor King, myself, and 

 other palaeontologists, to the genus Betzia ; and this is where I must leave them, at any 

 rate until the internal arrangements of Betzia Adrieni shall have been investigated. 



At p. 29 of the ' Twelfth Annual Report of the Regents of the State of New York,' 

 Professor Hall describes his genus Bhynchospira and his B. formom and B. evaac, 

 which much resemble, except in size, the Betzia Bouchardi of our Upper-Silurian rocks. 

 Mr. Whitfield informs me also that my Betzia Salteri is a true Bhynchospira, and that he 

 has an undescribed species very like it from Tenessee. 



At p. 125 of my 'Silurian Monograph,' I fully described the exterior characters of 

 B^. Salteri^ and noted that it was provided with spiral appendages. The Rev. Norman 

 Glass has, at my request, developed in a most complete and admirable manner the spiral 

 appendages, their attachments to the hinge-plate, as well as their loop, in several 

 examples. 



The spirals are somewhat oval in shape, and each spiral is found to consist of about 

 ten convolutions. The two principal stems of the spiral coils are attached to the hinge- 

 plate, and, after extending a little way into the interior of the shell between the spirals, 

 are suddenly bent backwards and upwards towards the hinge, and after forming a curve 

 converge to about half the length of the spiral, giving forth at that place short converging 

 lamellae, which are slightly or more strongly undulated in shape, and which proceed straight 

 across between the spirals to their ventral side before uniting in a sharp angular point. 

 This point is turned upwards more or less gently or abruptly almost immediately behind the 

 primary lamellae on the ventral side. The end of the loop which is thus turned upwards 

 varies in length in different specimens, never being very long, and sometimes being barely 

 perceptible. In some exceptional cases the loop differs from the description here given 

 in its having an upward slope, instead of proceeding straight across. Each of the two 

 primary lamellae diverge again as they proceed towards the front, and by a gentle curve 

 form the first spiral coil. 



Mr. Glass has also developed several typical examples of Plall's B. evax from the 

 Niagara group of Waldron, Indiana, and has found that its interior characters are exactly 

 the same as above described for B. Salteri. (Sil. Sup., PI. IV, fig. 19.) As we have described 

 to be the case mBetzia Salteri, the loop in some cases slopes more upwards than in others. 



Betzia principally differs from Nucleospira in the larger number of its spiral convolu- 

 tions, and in the hook-like attachments of the primary lamellae to the hinge-plate being 

 shorter and not strongly curved. It differs also in the loop being slightly more distant 

 from the hook-shaped processes. 



Betzia Salteri occurs throughout the Wenlock series of Shropshire, but is not 

 common in the shales that overlie the Wenlock Limestone, or in the Lower-Ludlow Shales. 



