THE FAMILIES AND GENEKA OF BATS. 
27 
- 2 3 . 1 . 
4 5 6 - 
1 2 -. 1 . 
- 2 - 456 - 
- 2 - 1 . 
4 5 6 7 . 
1 1 . 
- 2-4567 
- 2 -. 1 . 
-2 3 4 5 --. 
. 1 . 
- 2 3 4 5 6 - 
- 2 -. 1 . 
4 5 -- 
1 2 -. 1 . 
i 
i 
1 
1 
= 26 . 
= 26 . 
-- 24 . 
Diphylla. 
Eomops, Molossops, (part; 
Nyctymene. 
Cheiromeles, Molossus. 
=20. Desmodus, Disemus. 
It will be noticed at once that certain formulas are characteristic 
of particular groups, or rather that a given formula never occurs in 
widely separated families. Thus, among the genera with 31 teeth 
-2 3. 1. -23456- 
the formula 
is confined to the Pteropidae, 
1 2 -. 1. - 2 3 4 5 6 7 
-2 3. 1. - -345 67, ,, ™ , ,-2 3. 1. - 2- 4567 
1 2 -■ 1. - 234567 t0 the ^lostonncte, and 1 2 3. 1. - 2 - 4 6 6 7 
to the Vespertilionidae. Similarly among the 32-toothed genera the 
formula 
-2 -. 1 . - 2-4567 
1 2 3. 1. - 2 -4 5 6 7 
-2 3. 1. --34567 
is peculiar to the Embalionuridae, 
-2 3. 1. 4567 
1 2 -. l. - 2 - 4 5 6 7 t0 thS Ph y llostomid ®’ and 12 3. 1. - 2- 4567 
to the Vespertilionidae. The only formulas that occur in two or more 
2 3. 1. - 234567 
families are 
12 3. 1. - 234567 
: 38, found in the Natalidae, Thyr- 
- 2 -. 1 . • 4 5 6 7 
30 
opteridae, Myzopodidae, and Vespertilionidae, — ~ ^ ± § q y 
found in 9 genera of Vespertilionidae and 1 of Molossidae ( Mormop 
terns), and 
-2 -. 1. 4567 
= 28, found in two aberrant genera 
1 2 -. 1. - 2 - 4 5 6 7 
each of Vespertilionidae ( Antrozous and Tomopecis ) and Molossidae 
(. Molossops , part, and Mormopterus , part). Even in these excep- 
tional cases, however, the families involved are not distantly allied. 
The only teeth that are never absent are the canines, the last pre- 
I. 45 
molar and the first molar, * ----- — those never present 
the first upper incisor and the first upper and lower premolar, 
— 2 3. 1. — 234567 
6lr3 -iffi r 2 3 4 5 6 7 ‘ ^ le re( ^ uc ^ ons by which the various formulas 
have been produced appear to be as follows: 
Incisors . — In the upper jaw the permanently missing incisor is 
without much doubt the first. This is indicated, as shown by Winge, 
by the correspondence of the two upper teeth with the two outer of 
the lower jaw when the maximum set is present, and also, even more 
strongly, by the general tendency throughout the group for the pre- 
maxillaries to become reduced, particularly along the inner edge. 
This would inevitably result in eliminating that part of the bone in 
which the first incisor grows. Of the remaining upper incisors it is 
