﻿300 DR. A. VAUGHAN ON THE PALJEONTOLOC4ICAL [May 1905, 



Spirifer. 

 Spirifer aff. clathratus, M'Coy, Yaughan. (PI. XXVI, fig. 5.) 



As interpreted in Vanghan, Proc. Bristol Nat. Soc. n. s. vol. x (1903) 

 pp. 125-27 & pi. ii, figs. 3-3 c. Also compare L. G. de Koninck, ' Sur 

 le Spirifer mosquensis & sur ses Affinites avec quelques autres Especes du 

 meme Genre ' Bull. Mus. Roy. Hist. Nat. Belg. vol. ii (1883) pp. 371-402 : 

 Sp. tomacensis, de Kon. p. 386 & pi. xiii, figs. 1-9, and Sp. cinctus, 

 A. de Keys. p. 383 & pi. xv, figs. 3-8. 



The characters of this bisulcate Spirifer have been fully discussed 

 in my paper above cited. I have merely to add that the two forms 

 (which were erroneously described as mutations) can only be re- 

 garded as varieties, which are continuously connected by intermediate 

 stages ; their ranges are approximately the same, and therefore 

 their distinction is a matter of no strati graphical importance. 



The large form, however, figured in pi. ii, fig. 3, Yaughan, op. 

 cit., resembles Spirifer ductus, and is only common from the top of 



Z r up to y. 



Sptrifer aff. mosquensis, Eischer, de Kon. 



Compare L. G. de Koninck, Bull. Mus. Eoy. Hist. Nat. Belg. (1883) p. 379 

 & pi. xiv, figs. 1-11. 



A few specimens of a form which is, apparently, closely allied to 

 this species have been found in D 2 (Avon section and Wick). 



It is extremely interesting to note that the gens occupies the 

 same position in the Bristol area as it does in Eussia, namely, above 

 the maximum of Productus giganteus. 



Spirifer cf. g-randicostatus, M'Coy, Davidson (pars). 



Non Spirifera grcmclicostata, M'Coy, ' Brit. Palseoz. Foss.' 1851, p. 417 & 

 pi. iii D, fig. 29. 



A Spirifer, similar to that figured by Davidson, in ' Monogr. 

 Brit. Eoss. Brachiop.' vol. ii (1858-63) pi. vii, fig. 8, occurs rarely 

 in D 2 , in the Bristol and surrounding areas. 



Spiriferina. 



Spiriferina octoplicata (Sow.), Davidson. (PI. XXYI, fig. 6.) 

 Compare Davidson, op. cit. pi. vii, fig. 40 & pi. liv, fig. 10. 



The form figured by Davidson, op. cit. pi. vii, figs. 60 & 61, under 

 the name of Spiriferina partita, Portlock, is extremely common at 

 Horizon (3. It is connected, by insensible gradations, with the 

 more typical form which is characteristic of K. 



Syringothyris. 



Syringothyris aff. laminosa (M'Coy), (Davidson) pars. 



Compare Davidson, ' Monogr. Brit. Foss. Brachiop.' vol. ii (1858-63) pi. vii, 

 figs. 18 & 19 (' Spirifera ' laminosaj, and the area as shown in fig. 17. 



The nature of the area, of the ribbing, and of the mesial fold and 

 sinus are well expressed by .Davidson's figures. The test is per- 

 forated by sparse tubuli (punctas). 



The very important internal characters are as follows : — Brachi 



