﻿JURASSIC AND TRIASSIC BRACHIOPODA. 



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they then approach somewhat in shape to Ter. Phillipsii, but may always be distinguished 

 by their smaller size and their inflated beak from the varieties of T. Phillipsii where the 

 folds are of less length than in the type. It is certain that most of the biplicated forms 

 of Terebratula, whether they occur in the Jurassic, Cretaceous, or Tertiary formations, 

 can, by the means of exceptional examples, be more or less intimately connected, forming 

 a great group of shells characterised by two folds. Indeed, it is a question still to be 

 solved whether some of these have not continued to live on through the Jurassic and 

 Cretaceous into the Tertiary period, for in all these formations there are some of these 

 prevailing and perplexing forms. They appear, however, to have become extinct at the 

 conclusion of the Tertiary period, since they are not, as far as our present knowledge 

 bears us out, represented in the living state in our seas. Now, although these biplicated 

 forms can be more or less nearly connected by taking exceptional or passage forms into 

 consideration, most of them are, as far as species will permit, somewhat dissimilar 

 when adult examples are taken into consideration, and it would be quite wrong to seek to 

 unite into a single species T. Phillipsii and T. globata, or many others that might be 

 named. T. perovalis and T. globata are, as far as species go, distinct, although they may 

 in a manner be connected by passage forms to T. intermedia, T. ventricosa, T. bisuffarcinata, 

 and others. For the purposes of geology certain named forms are absolutely necessary ; but 

 in defining these the palaeontologist must not forget general characters, or seek to elevate 

 to the rank of a species every deviation from the typical form, typical only in his own 

 imagination, and because they have been selected by him to represent his idea of his 

 species. 



T. globata attained 18 lines in length, by 17 in width, and 12 in depth. It occurs in 

 many localities where the Inferior Oolite is found. Sowerby's original type came from 

 Nunney, near Frome. It is found likewise in the Fuller's Earth near Bath. 



103. Var. Fleischeri, Oppel Dav., Ool. Mon., PI. XIII, fig. 7 ; Appendix to Vol. I, 



PI. A, fig. 18 ; and Sup., PI. XVII, fig. 2. 



Terebratula Fleischeri, Oppel. Jura-Formation, p. 497, 1856. 



According to Oppel's view this shell is elongated oval and somewhat closely bipli- 

 cated near the front, with valves smooth and very convex ; beak moderately incurved, 

 and truncated by a circular foramen slightly separated from the hinge -line by a deltidium 

 in two pieces. Some specimens have measured 17 lines in length, by 12 in breadth, 

 and 11 in depth. It occurs, with my typical form of T. globata, in the Inferior Oolite of 

 Birdlip, near Cheltenham. 



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