CHORD ATA 219 



types, are regarded as defective, aberrant offshoots of the main 

 vertebrate arachnid phylum." 



The recent discovery by Prof. J. Kiaer of well-preserved fossil 

 Ostracoderms in the Silurian rocks of Norway, and the collection by 

 Professor Stenso of perfectly preserved fossils of one of them, Cepha- 

 laspis, from the Devonian rocks of Spitzbergen, have given new evi- 

 dence to support Professor Patten, and gratified the friends of this 

 "grand strategist of evolution.!' Serial sections of the Spitzbergen 

 specimens studied by Patten indicate that the "radiating bony chan- 

 nels for the cranial nerves, and many other architectural features of 

 the anatomy of the head conform to the general plan seen in the 

 heads of fossil Enrypterids and other arthropods." ^ 



Professor Patten has made three expeditions to the Island of 

 Oesel excavating fossils and in 1931 found six new species of ostraco- 

 derms.^ 



Annelid Theory. — The Annelid theory advanced by Dohrn, 

 Semper, Beard and Delsman postulates that an annelid is turned 

 over on its back and develops a mouth and anus. The notochord 

 is represented in the annelids by a bundle of fibers running along the 

 nerve chain, occupying a similar position to the notochord of the 

 chordata and apparently serving the same function of support. 

 Connective tissue encloses both nerve cord and fiber bundles 

 (Faserstrang.) just as the notochord and the spinal cord are 

 enclosed in the higher type. 



The segmentally arranged nephridia correspond to the primitive 

 kidney tubes of the vertebrate kidney. The segmentally arranged 

 ganglia around the appendages of some worms ( Nereis) may cor- 

 respond to the branchial and lateral sense organs of the Ichthyopsida 

 and the ganglia of some of the cerebral nerves. 



The fundamental relationship of the nervous system and the 

 vascular system to the digestive tract as found in the annelids is 

 quite comparable to the condition in the primitive vertebrates. 



Wilder has indicated the present trend away from the Annelid 

 theory and points out that a worm-like ancestor does not necessarily 

 mean that we must accept an annelid. (See trochophore, p. 125.) 



5 Gregory, W. K., 1928, in Creation by Evolution, edited by F. Mason, Mac- 

 millan Co., New York. 



* Consult Patten, W., 1931, New Ostracoderms from Oesel. Science, vol. 73, 

 no. 1903, pp. 671-673. Tremataspis has, as predicted, paired jaws or oral arches, like 

 those in embryonic vertebrates (frog) and which work sidewise, not forward and back- 

 ward as in the united oral arches of adult vertebrates. 



