Lemur Linnæus included not only all the then known forms now recognized as the suborder Lemuroidea, but also the "Flying Lemur" Galeopithecus, which properly either forms an order by itself with no near affinities with the Primates, or is at most a suborder of the Cheiroptera. (2) The definition also included the bats (Vespertilio), an order more nearly related to the Insectivores than to the Primates. Many of the characters selected by Linnaeus for his ordinal diagnoses were of the "adaptive" or superficial kind which are now known to have been most easily modifiable by changes in the external or internal environment. The reason for this mistake (a mistake from which few naturalists were free even down to our own generation) was that Linnæus regarded the mode of sustenance of a group as one of its most deep-seated attributes, most surely indicative of more or less hidden affinities with other groups. For it is well known that Linnæus was constantly searching for natural groups, although he did not realize that the natural affinity of the members of the larger groups was due to descent from common ancestors, just as in the case of members of the same species. An example of his reliance upon sustenance is seen in his definition, in the tenth edition of the "Systema," of the order Feræ, the Carnivora of later authors. Here "sustenance by rapine, upon carcasses ravenously snatched" is evidently felt to be connected with "front teeth in both jaws: superior vi, all acute," with "laniariform teeth [canines] solitary," with "claws on the feet acute." But one of his dicta in botany was that a character of great systematic importance in one group may be very variable in another, consequently he did not mention sustenance under Bruta, but contented himself with the two characters "front teeth none either above or below" and "gait awkward (incessus ineptior)." As this order included the elephant, the manatee, the sloth, the great anteater and the scaly ant eater, it has been justly cited as a grossly unnatural assemblage; and the grouping accounted for by Linnæus's ignorance of the animals composing it. But I am more disposed to attribute it first to his habit of searching for hidden affinities below the most obvious external differences, as when he placed the seals in the order Feræ, joined the bats with the Primates, the horse and the hippopotamus, the rhinoceros with the Rodents, and the pig with the Insectivores (in the order Bestiæ). That Linnæus recognized that the ordinal classification of the mammals was a difficult problem is shown by the conspicuous changes (not always improvements in our eyes) and redistributions which he made between the first and "tenth" editions of the "Systema" and further by the fact that Erxleben who revised and extended the Systema (1777) abandoned the ordinal divisions entirely and merely listed the genera seriatim. The difficulty of the problem in indi-
