326 The American Geologist. ^^^' i^"*- 
For complete proof of any phylogenetic theory, the arguments 
from embryology and from comparative anatomy must be supported 
by palaeontology. Professor Patten's theory lia.s in its favor the fact 
that his ancestral forms had hard shells and hence are preserved, 
hence complete proof or disproof should be only a matter of time and 
work. None of the other current theories of vertebrate origin — (An- 
nelid; Enteropneusta ; Prosopygia ; Nemertine) — can ever receive com- 
plete demonstration, since the animals are soft bodied, and not preserved 
as fossils. Nevertheless professor Patten has not yet proved either of 
his two propositions. 
That the general affinity of the ostracoderms is with the vertebrates 
has been recognized since they were first described ; yet the essential 
features of vertebrate organization — (the presence at some stage of 
development of gill slits, notochord, and dorsal nerve tube) — ^have 
never been definitely made out. Their remarkable resemblance to 
trilobites has also been frequently commented upon. Professor Patten 
takes up the various anatomical features of Pteraspis and of Ceph- 
alaspis, and draws a comparison between them and analogous structures 
in arthropods, finding many points of similarity. 
But one point which professor Patten entirely ignores in his re- 
searches is the fact that the sharks are the oldest vertebrates, being 
recognized as ancestral not only to higher fishes but to the land ver- 
tebrates as well. There is a wide break between Cephalaspis and 
Cladoselache, and it appears impossible to derive the shark line, which 
is undoubtedly ancestral to higher forms, from an ostracoderm ances- 
tor. Whatever their systematic position, the ostracoderms appear to 
be, like Palaeospondylus and the arthrodires, a side branch from 
the early vertebrate stem and not a stage through which the whole 
veilebrate phylum passed. 
Professor Patten's paper consists of a very carefully worked out 
description of the fossils ; of a review of the authoritative opinions of 
former observers ; and of a statement of his own opinion. i. h. 0. 
MONTHLY AUTHOR'S CATALOGUE 
OF AMERICAN GEOLOGICAL LITERATURE 
ARRANGED ALPHABETICALLY. 
ADAMS, F. D. 
New nepheline rock from the province of Ontario, Canada. (Am. 
Jour. Sci., vol. 16, pp. 269-276, Apr., "i904.) 
AGUILERA, J. G 
The discovery of the Bacubirito meteorite. (Am. Geol., vol. 33, 
p. 267. Apr., 1904.) 
ANONYMOUS. 
The coal fields of Colorado. (Bull. Sch. Mines, Colo., vol. 2, p. 11. 
Jan., 1904.) 
