TEREBRATULA. ' 7 



order to show the apparently very close connection existing between all our hitherto dis- 

 covered British Carboniferous and Permian Terebratulae, and which are in all probability 

 mere variations in shape of a single species, and it is my impression that the Devonian 

 form above described is nothing more than another slight modification of the Carboniferous 

 species, or, in other words, that both the Carboniferous and Permian shells are 

 derived from, or are mere slight modifications of the Devonian one above described. Mr. 

 Bouchard is, however, of opinion, that figs. 1 to 8 of our plate should be referred to 

 Scholtheim's Ter. clongata, a form found in the Permian strata of England and of the 

 Continent, as well as in the Devonian Limestone of Grand in the Hartz ; at Ferques, near 

 Boulogne, and in that of the Eifel, I am quite ready to admit with Mr. Bouchard, that 

 some of our Barton and Lummaton specimens do exactly resemble young examples of 

 T. clongata, which have both valves convex, and a nearly straight front line ; but it must 

 also be remembered that in adult and well-shaped specimens of Schlotheim's species the 

 ventral valve presents in profile a regularly arched curve from the extremity of the 

 beak to the front, with a wide depression or shallow sinus, commencing towards the 

 middle of the valve and extending to the front, producing in the frontal margin a convex 

 and elevated curve, varying in degree according to age and individual, but which is not 

 the usual aspect of Barton and Lummaton species. It appears to me probable that the 

 shell under description will be more correctly located with T. sacculus, and of which 

 T. hastata and T. Glllingensis are varieties, for many of our Lummaton specimens exactly 

 resemble each of these modifications, and which we consider to belong to a single species. 

 I should also mention that Mr. Carrington has recently discovered several examples of 

 T. sacculus with colour-bands similar to those we have described in T. hastata, so that 

 one of the objections brought forward by some palaeontologists to the uniting of those two 

 so-termed species is now removed. 



It is quite evident that Schlotheim originally applied the name of T. clongata to the 

 Permian form, but that subsequently he referred some Devonian specimens to his Permian 

 type, and I have shown in PL 54, figs. 1 — 4 of my Carboniferous Monograph, that many 

 specimens of the Carboniferous T. Iiastata and the Permian T. clongata are undis- 

 tinguishable. 



From these considerations I quite coincide in the opinion expressed by Mr. Bouchard, 

 that it would be only encumbering science with another useless synonym were we to 

 give to the Devonian form a separate specific designation, and as that of Sacculus 

 is the oldest on record, it would I think be prudent to make use of it in the 

 present instance. T. sacculus has been also found in the Middle Devonian Limestone of 

 the neighbourhood of Plymouth, and in the Upper Devonian (?) brown grits of I\lton and 

 Marwood in Devonshire. 



