386 GENERAL SUMMARY TO 



It likewise appears that the earliest forms among the Brachiopoda, as far as our 

 present state of information will carry us, are referable to the genera Lingulella and 

 Discina, but in rocks somewhat later in age (the middle beds of the Menevian group 

 or Lower Lingula-flags) to those in which Lingulella and Discina are found, there 

 appears a species of Orfhis (0. Ilicfoi) which, as far as I am aware, would be the 

 earliest representative of the division Clistenterata. Since the appearance of this Orthis 

 both divisions have continued to be represented without apparently showing a tendency 

 to pass one into the other. Now although certain genera, such as those above named 

 and a few others, have enjoyed a very considerable geological existence, by far the larger 

 number of the others, such as Slringocephalus, Uncites, Porambonitcs, Davidsonia, 

 &c, made their appearance very suddenly and without any warning, and after a 

 comparatively short time disappeared in a similarly sudden or abrupt manner. They are 

 all possessed of such marked and distinctive internal characters that we cannot, in the 

 present state of our knowledge, trace between them and associated or synchronous genera 

 any satisfactory or direct evidence of their being either modifications of one or the other, 

 or being the result of descent with modifications, although such may be the case, for all 

 we know to the contrary. 



Darwin, whose name will ever be held, like those of Newton, Herschel, Harvey, 

 Faraday, Owen, Lyell, as one of the most eminent among the men of science to which 

 this country has given birth, was always most anxious that his views should be tested 

 and worked out in some detail, and in a single group, and in several communications 

 he urged that I should do this with the Brachiopoda ; for he was himself fully aware of how 

 many problems still remained to be solved before his theory could be finally admitted. 

 In a letter directed to me, and dated the 26th of April, 1861, he says, " I do not know 

 whether you have read my ' Origin of Species.' In that book I have made the remark,, 

 which I apprehend will be universally admitted, that as a whole the fauna of any 

 formation is intermediate in character between that of the formation above and below. 

 But several really good judges have remarked to me how desirable it would be that this 

 should be exemplified and worked out in some detail, and with some single group of beings. 

 Now, every one will admit that no one in the world could do this better than you with 

 the Brachiopods. The result might turn out very unfavorable to the views which I hold ; 

 if so, so much the better for those who are opposed to me. But I am inclined to 

 suspect that, on the whole, it would be favorable to the notion of descent with modifi- 

 cation. I can hardly doubt that many curious points would occur to any one thoroughly 

 instructed on the subject who could consider a group of beings under the point of view of 



Further the inequality in evolution is one of the causes of the variety of aspects that the history of the 

 world presents. At all geological epochs, except perhaps at the outset, there have been creatures in the 

 first stage of evolution, others that have reached the second, others the third, and others the highest. It is 

 from these inequalities that has resulted in part the marvellous beauty of nature in all geological times." 

 See also a paper by M. de Rainecourt "Sur quelques observations sur les modifications des cspeces," 

 ' Bull. Soc. geol. France,' 3rd ser., vol. xi, p. 472, 1883. 



