452 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1907. 
of science over popular impressions; of anatomical consideration over 
superficial views. 
But mingled with the great benefactions were many views which 
long influenced naturalists, but which modern zoology has over- 
thrown. 
LINNEZAN CLASSES. 
After the tentative arrangements published in the original first, 
second, and sixth editions of the “ Systema,” Linné thoroughly re- 
vised his work, and first consistently apphed the binomial method of 
nomenclature to all species in the tenth edition, published in 1758. 
Six classes were admitted with equal rank, no category being recog- 
nized between the class and kingdom. The classes were the Mam- 
malia or mammals, Aves or birds, Amphibia, Pisces, Insecta, and 
Vermes. The first four of these classes correspond mainly to the 
Aves and nameless groups of Ray. 
During the Linnean period of activity the invertebrates were little 
understood, and his treatment of that enormous host, referred to his 
two classes Insecta and Vermes, contrasts rather than compares with 
that at the present time. Naturally, the vertebrates were much better 
comprehended, and all such then known, with a single exception, 
were distributed among four classes just named, the Mammalia, 
Aves, Amphibia, and Pisces. The solitary exception of exclusion of 
a true vertebrate from its fellows was the reference of the genus 
Myzxine to the Vermes, next to Teredo, the shipworm. The first two 
classes were adopted with the same limits they now have, but the 
Amphibia and Pisces were constituted in a truly remarkable manner. 
The class of Amphibia was a creation of Linné, and was simply con- 
trasted with his Pisces*by having a lung of some kind or other 
(“ pulmone arbitrario”), while the Pisces have exposed branchi 
(“branchiis externis”). The Amphibia, thus defined, were made to 
include as orders: (1) Reptiles, or Reptilia, having feet; (2) Ser- 
pentes, footless, and (8) Nantes, having fins. 
Under the Nantes were first grouped the lampreys, the selachians, 
the anglers (Lophius), and the sturgeons (Acipenser). In the tweltth 
edition were added Cyclopterus, Balistes, Ostracion, Tetrodon, Dio- 
don, Centriscus, Syngnathus, and Pegasus. The Nantes were added 
to the Amphibia partly because of the assumption that thé branchial 
pouches of the lampreys and the selachians were lungs and partly on 
the authority of Dr. Alexander Garden, of Charleston, S. C., who mis- 
took the peculiar transversely expanded and partly double air-blad- 
der of Diodon for a lung. With such errors of observation as a basis, 
Linné apparently assumed that all the associated genera also had 
lungs. Gmelin, in his edition of the “ Systema Natur ” (generally 
* 
