62 BRITISH CRETACEOUS BRACHIOPODA. 



The next point (and one which has given me, perhaps, more trouble than almost any 

 other in this work) was the endeavour to find out to what species these shells really be- 

 longed, and it was not until after two excursions to Farringdon, and the minute examina- 

 tion of more than three hundred examples, collected in the same spot 'by Messrs. Sharpe, 

 Lowe, Forbes, Waterhouse, Morris, myself, and others, that I at last determined to consider 

 the shells above described as a small race or variety of Terebratula Tornacensis, D'Archiac ; 

 and, indeed, several of the forms found in that locality are only dwarf races; thus, Tere- 

 bratella Menardi and T. depressa, Lamarck, have not there attained the full size of those 

 species found in the Upper Green Sand of Mans ( France), or the Tourtia of Belgium; and it 

 appears evident that local conditions during the formation of the Farringdon deposits were 

 unfavourable to the full development of many of the forms of Brachiopocla, and which is 

 no doubt the true cause of the stinted growth observable in many of the species. 



The next point to investigate is whether T. Tornacensis is the oldest denomination the 

 species has received ? and I am still uncertain if Ter. p/iasiolina, Lamarck 1 (published in 

 1819, but without figure), may not be a young state of Vicomte d'Archiac's species; but 

 as doubts at present involve that question, we will give preference to the Vicomte's claims, 2 

 and endeavour to discuss the value of some of its probable synonyms. 



M. D'Orbigny considers the following names to be synonyms or varieties of 

 Terebratula biplicata (Brocchi) : — Ter. Tornacensis, Bouei, crassa, Bobertoni, crassificata, 

 rustica, JBoubei, Virleti, revoluta, sub-pectoralis, Keyserliiigii, and Tchiatcheffii (D'Archiac), 3 

 but I differ from the author of the Palgeontologie Francaise, (as elsewhere stated 1 ) in the 

 following particulars. I am of opinion that Ter. biplicata (Brocchi) is the same 

 shell as that of Sowerby, which M. D'Orbigny considers distinct; the last-named 

 author considers Ter. Tornacensis equivalent to T biplicata (Brocchi), and of T. biplicata, 

 Sow., forms a new species, to which he has applied the name T. Dutempleana. We 

 therefore, both so far agree in the opinion that perhaps there may exist two species, but 

 disagree as to which Brocchi's figure should belong. I admit with M. D'Orbigny that 

 Ter. Boemeri, Bouei, crassa, crassificata, rustica, and perhaps Ter. Murcldsoni and 

 Tchiatcheffii, D'Archiac, may be only variations in age, &c, of Ter. Tornacensis ; but I 

 am not yet prepared to consider as such Ter. Virleti and T. revoluta, D'Archiac, and still 

 less Ter. Bobertoni and T. sub-pectoralis of the same author. 



Mr. Sharpe and other palaeontologists identify our Farringdon shell with Ter. 

 Boemeri; but after a lengthened examination, I was unable to find grounds of sufficient 

 value for considering the last specifically different from T. tornacensis. It is true our British 



1 Animaux sans Vertebres, vol. vi, No. 29, 1819. 



2 Rapport sur les Fossiles du Tourtia. M6m. Soc. Geol. de France, vol ii, 2d series, p. 316, &c, and 

 plates xviii and xix, 1847. 



3 Prodrome, vol. ii, p. 172, 1850. 



i See Obs. to our description of Ter. biplicata. 



