26 
DR. W. KOWALEVSKY ON THE 
figured by Pictet belonged undoubtedly to an Ungulate with only two metatarsals. 
At all events, these Eocene Hyopotamidce seem to form a separate group ; and as soon 
as their organization is better known, they will certainly be generically separated from 
the true Hyopotami. As the matter now stands, however, this Hyopotamus ( Cainothe - 
Hum ) Henevieri is the smallest representative of the family, being hardly larger than a 
good-sized rat ; the Hyopotamus Gresslyi had perhaps the size of our recent Tragulidce. 
Between these small Hyopotami and the largest Hyopotamus bovinus, Ow., we have all 
the intermediate sizes distinguished as separate species’under the names of Hyopotamus 
porcinus, Gerv., crispus, borbonicus, velaunus, Aym., leptorhynchus, platyrhynchus, vec- 
tianus, Ow., and finally bovinus. All these numerous species were, for the most 
part, founded merely on real or supposed differences in the size of the true molars, 
no author having figured or described any other part of the skeleton. Now, as every 
naturalist is aware, there can be no worse method of specific distinction than size, 
especially in richly developed families. Take our living Ruminantia, imagine them 
to be extinct, and some future palaeontologist trying to give them generic and 
specific names by the characters of their upper and lower molars. I do not think he 
could arrive at any thing approaching truth. We may certainly form a large series 
of ruminant molars, entirely similar in shape, and ranging in size from the small 
Antilope pygmcea to the largest Antelopes and Bovidae*, and then distribute all this 
assemblage of teeth into different species according to size ; but the scientific value 
of such species would be indeed very doubtful. Still this is what we see constantly 
done in palaeontology. In my opinion, we have, in most cases, not the least chance of 
hitting right in establishing specific distinctions on fossil remains; and most of the 
published species of extinct animals are certainly only productions of our palaeonto- 
logical methods of inquiry, which had no real distinction whilst living. On the other 
hand, it is just possible that the real number of so-called distinct species was greater 
than we can distinguish by fossil remains ; at all events we have very little security that 
most of our specific distinctions correspond to the real state of things which existed in 
past geological time. Seeing the impossibility of arriving at any thing like an accurate 
knowledge of the specific distinction of extinct forms, it would be much more profitable 
to science if we were to give a pretty large range, as far as size is concerned, and concentrate 
all our discriminating powers on such characters as are really organic and fundamental, and 
may be taken as a basis for generic or subgeneric distinction. To found a new genus, 
a palaeontologist is required to adduce some good reason for doing so; he is obliged to 
point out some organic difference, and this leads to a more complete study of the fossil 
forms; while the laxity with which we regard species requires, in a great majority of 
cases, no other reason than the phrase “ this tooth seems to me to be specifically distinct 
from one already described,” and a new name is formed which goes to the large 
number of others uselessly obstructing the science. Every one who has tried to ascer- 
* The upper molars of some Ruminantia sometimes present distinctive characters in the form of additional 
pillars, but these are often present or absent in widely different forms. 
