844 The American Naturalist. [October, 
Some had “the vertebral bodies represented by three segments 
each, a basal intercentrum and two lateral pleurocentra ; ” 
these were named “ Ganocephali” and “ Rhachitomi.” Some 
“differ remarkably from all other Vertebrata in having be- 
tween the centra another set of vertebral bodies, so that each 
arch has two corresponding bodies ;” these were called “ Em- 
bolomeri.” 
In tracing the development of these bones, Cope came to the 
conclusion that they were only partially represented in higher 
or more specialized types; they did not become consolidated, 
but one or the other became reduced and finally lost or at least 
greatly atrophied. In the living amphibians the vertebral 
centra are homologous only with the intercentra, while, on the 
contrary, the centra of the reptiles, birds and mammals are 
represented by the pleurocentra of the Rhachitomes. 
The studies of Cope on those classes which had earliest at- 
tracted his attention were more nearly completed than for any 
others. Many years ago he had contemplated the publication 
of monographs of the amphibians and reptiles of North Amer- 
ica and happily he had at last finished his work. 
In 1889 his monograph of the “ Batrachia of North Amer- 
ica” was given to the world as a Bulletin of the United States 
National Museum (No. 34). It forms a goodly volume of 525 
pages illustrated by 81" plates and 120 figures inserted in the 
text. No large country has a more elaborate and scientific 
exposition of the class than is given in this volume. A syn- 
opsis is furnished of all the families and genera wherever 
found, and detailed descriptions are supplied for all the groups 
and species represented in the zoological realm of North Amer- 
ica, 31 genera and 107 species are recognized, and of these 
Cope had first made known about a quarter, 7 of the genera 
and 27 of the species having been described by himself. 
Shortly before his death, and during his last visit to Wash- 
ington he delivered to the National Museum the report on all 
the reptiles of North America which he had been long prepar- 
ing. This was prepared on the model of his “ Batrachia of 
North America,” but will, of course, be a much larger work, 
' 18 The last plate is nambered 86, but five were cancelled, 80, 81, 82, 84 and 85. 
