6 BRITISH OOLITIC AND LIASIC BRACHIOPODA. 



in the most liberal manner placed the original collection of the M. C. at my disposal ; and 

 with the assistance of Mr. Waterhouse, we have endeavoured to clear up the original 

 types, some of which were merely synonyms, such as Ter. Triquetra, orbicularis, f areata, 

 lata, &c. &c. 



The difficulty I have encountered, in my endeavours to place the different shells hitherto 

 discovered in their proper places, is such, that I feel convinced numerous errors will have 

 been committed, which I hope other observers and future discoveries may correct. No class 

 of shells is more variable in their form, and the instances in which the former pass into 

 each other are so numerous, that by some one or other character we might readily attach 

 most species together. We often forget, that among the species of Brachiopoda there must 

 have existed different races, as well as in those of other classes, arising from local conditions, 

 and by the little attention paid to these circumstances species are made out of more 

 varieties. It is certain that many species were ornamented by colour, such as we perceive 

 among the recent shells ; this colour, which would have been a great help, we are deprived 

 of; its existence, however, is proved by accidental specimens found occasionally possessing 

 traces of it, — we know that some Devonian species were spotted with red. Ter. Hastata, 

 Communis, and others irregularly and longitudinally striped, probably also with red, as we 

 see in Bouchardia rosea; and among the oolite species it is more than probable, from traces 

 discovered by M. Deslongchamps, that Rhynchonetta spinosa was of a red colour, as well 

 as some of the cretaceous species. From the limited resources often left us by fossilization 

 we are not always able to trace correct boundaries to species ; but we should endeavour to 

 do so where characters are sufficiently marked to be constant, and which may serve as 

 conventional points of comparison and reference. 



After many years of researches, M. Deslongchamps 1 published his views on the classi- 

 fication of the Brachiopoda found in Normandy — a paper I have long appreciated, but which, 

 to my surprise, is little noticed by those who have written on a similar subject. In it that 

 distinguished and conscientious author states, that after many different attempts to classify 

 the Brachiopoda, he found the best outward characters to consist in the shape and position 

 of the foramen ; since which period Messrs. Morris, D'Orbigny, and others, have thrown 

 much additional light on this point by the discovery that the form of the internal Apophy- 

 sary system also bore intimate relations to the form and position of the beak, foramen, and 

 deltidium. This, moreover, appears to be the best mode of proceeding where the internal 

 characters are hidden from our view ; but, while this character is of generic importance, it 

 does not always help us to separate species. M. Deslongchamps, in his table, proposes to 

 select a type and annex to it a number of allied forms, under the name of varieties : thus of 

 Ter. resupinata he mentions twelve varieties, of emarginata fifteen, of perovalis eleven, of 

 Conciuna twenty, &c. ; and he could have added many more had he operated upon a 

 larger collection ; and although I completely agree with M. Deslongchamps as to the 

 reality of his varieties, still this system would, it is to be feared, lead to great confusion, 



1 'Seances publiques de la Soc. Lin. de Normandie,' 1837, p. 30. 



