PRINCIPLES OF MORPHOGENESIS 13 



including among them the operculate coral Calceola. In 1849 King recognized 49 genera in 16 

 families, and Bronn in 1862 listed 51 genera. Hall and Clarke (1892-1894) added 58 new genera 

 and in their "Handbook of Brachiopoda" recognized 325 genera or subgenera. By 1913 (Zittel- 

 Eastman) this number had grown to about 450, Buckman alone added 5 1 new genera of rhynchonel- 

 lids in 1914 and now there are at least 750 genera or subgenera in good standing, in addition to some 

 200 rejected names, many of which will doubtless be revived. Of these 750 genera, one only belongs 

 with certainty to the order Palxotremata, 50 (7 7o) are Atremata, 47 (6%) Neotremata, 234 (31 %) 

 Protremata, and 41 7 (55%) Telotremata. The Paleozoic has about 500 genera, the Mesozoic about 

 180, and the Cenozoic-Recent about 75. 



THE GENUS CONCEPT 



"To no human question is there an immutable and final answer." — Bather 1927 



All paleontologists working to discern the genetic relations of fossils should study the Presidential 

 Address of F. A. Bather entitled "Fossils and Life," which was delivered before Section C of the 

 British Association for the Advancement of Science in 1920.'' This masterly address deals chiefly 

 with the philosophy of ancient life in relation to that now living under the influence of the environ- 

 ment — the leading influence making for genetic evolution as interpreted by both paleontologist and 

 neontologist. Bather says: 



Like Botany and Zoology, Paleontology describes the external and internal form and structure of animals and 

 plants; and on this description it bases, first, a systematic classification of its material; secondly, those broader 

 inductions of comparative anatomy which constitute morphology, or the science of form. Arising out of these 

 studies are the questions of relation — real or apparent kinship, lines of descent, the how and why of evolution — 

 the answers to which reflect their light back on our morphological and classificatory systems (p. 61). 



Paleontologists, unlike neontologists, are concerned with the "concept of time ... an orderly 

 and related succession, coextensive, in theory at least, with the whole history of life on this planet" 



Since the days of Linnasus, biologists have sought for "natural classifications," but back of 1 859 

 these were more arbitrary than natural j with the publication of Darwin's "Origin of Species," how- 

 ever, it has become more and more possible to determine the genetic relationships, or the "blood-red 

 clue of natural afiinity." 



Descent, then, is not a corollary of succession. Or, to broaden the statement, history is not the same as evolu- 

 tion. History is a succession of events. Evolution means that each event has sprung from the preceding one. Not 

 that the preceding event was the active cause of its successor, but that it was a necessary condition of it. For the 

 evolutionary biologist, a species contains in itself and its environment the possibility of producing its successor 

 (pp. 66-67). [Not until we pursue the "line upon line" method of paleontology shall we] have linked species into 

 lineages, can we group them into genera; not until we have unravelled the strands by which genus is connected 

 with genus can we draw the limits of families. Not till that has been accomplished can we see how the lines of 

 descent diverge or converge, so as to warrant the establishment of Orders (p. 70). 



It is undoubtedly true, as Gertrude Elles points out in her paper, "Evolutional Paleontology,"' 

 that species and genera have too often been made by paleontologists in the laboratory without the 

 knowledge of the field, since the strata entombing fossils are the only preserved environments. 

 Furthermore, only too often are species and genera made on the basis of chronogenesis and not on a 

 proved genesis, and most of our genera with large assemblages of species are polyphyletic in origin. 



The modern taxonomic trend based on evolution, as used by vertebrate paleontologists, is well 

 illustrated in the paper by H. F. Osborn bearing the title "Final Conclusions on the Evolution, 

 Phylogeny, and Classification of the Proboscidea. "" His viewpoint as to the value of the divisions 

 appears, however, to be an extreme one. Here we learn that Lydekker in 1886 knew of but two 



* Rept. British Assoc. Adv. Sci., Cardiff meeting, 1920, pp. 61-86. 

 ° Rept. British Assoc. Adv. Sci., Liverpool meeting, 1923, pp. 83-107. 

 •Proc. Amer. Philos. See., vol. 64, 1925, pp. 17-35. 



