1899 C. UPTON — BRACHIOPODA 123 



At that date (1853) the brachial valve was not known to 

 the author of the monograph. He subsequently discovered 

 that a complete specimen, which was stated to have been 

 found in the Oohte Marl of Brimscombe, w^as in the 

 possession of Prof. Sedgwick, and that Prof. McCoy had 

 already given it the M.S. name of T. galeiformis. This 

 specimen he figured in the appendix to Vol. I of the 

 monograph which was issued in the following year. 



Each of the figured specimens has a deep medio-longi- 

 tudinal sinus and one on each side. The present example 

 differs from the type in having fimbriate margins, and an 

 almost flat brachial valve. In other respects it is con- 

 formable. 



The tests of all TerebratultB are very thin, and conse- 

 quently fragile ; and in their more primitive forms have 

 no frontal folds. The first advance on the simple form 

 was the acquisition of a single, more or less elevated, 

 frontal fold. The next advance in development consisted 

 of a reflex fold in the centre of the simple fold ; and this 

 stage characterises the major portion of the Jurassic Tere- 

 brahda. It is obvious that the acquirement of such folds, 

 whether simple or complex, resulted in a gain of strength 

 without an excessive expenditure of material. In the pre- 

 sent specimen the required strength was obtained by the 

 acquisition of a number of small folds instead of in the 

 more usual manner. 



The exact locality of the specimen is unfortunately not 

 known ; but from the adherent matrix I have no hesitation 

 in stating that its horizon is the middle portion of 

 the Oolite Marl Series, which, south of Stroud, 

 usually consists of a white oolitic limestone. In respect 

 to horizon, therefore, it would agree very closely with all 

 other known specimens. 



It is a somewhat singular circumstance that this shell 

 should be associated with the only two other well-marked 



I 2 



