1877.] Microscopy. 501 
On THE CLASSIFICATION OF THE RECENT AND Fossil Fisnes. — 
Professor Cope has recently reviewed the structure of the fossil fishes, 
and proposed a number of necessary modifications of the system as left 
by Agassiz in the Poissons Fossiles. He has confirmed the views of 
various naturalists, that the class or sub-class Ganoidea of that author con- 
sists of heterogeneous materials, which must be distributed in a number 
of sub-classes. He recognizes four sub-classes of Pisces: namely, the 
Holocephali, the Dipnoi, the Selachii, and the Hyepomata. The last 
. named is proposed for that natural assemblage which possess a hyo-man- 
dibular bone articulated with the cranium, a maxillary arch, and no 
median axis of the basal portion of either pectoral or ventral fins. Un- 
der this group he arranges three tribes, namely, the Orossopterygia (or 
Ganoidea), the Chondrostei, and the Actinopteri ; the last made up of the 
Teleostei of Müller, and a few recent, and many extinct fishes referred 
by Agassiz and Müller to the “ Ganoidei.” Protessor Cope shows that 
Huxley’s “suborder Orossopterygia,” is also a heterogeneous assem- 
blage, many of the forms referred to it belonging to the Dipnoi, while 
others are true Hyopomata. 
The fossil fishes referred to the Actinopteri were found to be most 
nearly related to the order [sospondyli ; none of them presenting: near 
affinities to Lepidosteus, so far as discoverable. An exception to this 
statement, is the genus Dorypterus, which was regarded as typical of a 
new order presenting some relationship to Acanthopterygian orders. 
The order was named the Docopteri. The fossil families referred to the 
Lsospondyli, are the Sauropside (Sauroidei Agass. pt.), Lepidotide 
(Lepidoides Agass. pt.), Pycnodontide (Pycnodontes Agass. pt.), and 
Dupediide (Lepidoides Agass. pt.) 
MICROSCOPY. 
Tue New Mover ILLUMINATING ÅDJUSTMENT. — The plan of 
mounting the diaphragm , substage, and mirror upon a bar so hinged 
that they shall all swing concentrically around the object, now success- 
fully and extensively carried out by both Zentmayer and Gundlach, has 
given rise to an unusually interesting question of priority. The fact 
that the Rochester stands at the Centennial Exhibition, at the time of its 
opening, had the mirror stem hinged slightly below the plane of the object, 
has been not unreasonably, though incorrectly, understood by some writ- 
ers to indicate that there was at that time no intention to secure fully 
the advantages of the concentric swing. Mr. Gundlach, however, makes 
a fully conclusive explanation of the apparent discrepancy. As there is 
ho doubt that Mr. Zentmayer had then completed and made public his 
invention, it cannot be doubted that both parties fully matured the ps 
independently. 
So simple a device could hardly have escaped the efforts of previous 
workers. It was foreshadowed in the semi-cylinder of Mr. Tolles, with 
