100 MR W. E. HOYLE ON 
indicate respectively paleontology and zoology in general, 
are omitted from the heading and placed separately with the 
signature at the foot of the card. 
The classification number is given in full, so as to repre- 
sent as far as possible the whole subject of the paper. The 
great majority of papers fall under more than one heading. 
For instance, the memoir quoted in Example 2 treats of the 
teeth of the snake. Its class number consists of two parts— 
the number for ¢eeth, 14.31.4, and the number for snakes, 81.2; 
and these are both printed consecutively and separated by a 
colon, the systematic numbers being printed in heavy type, 
so that they may be readily distinguished. 
This paper is just as important to the student of teeth as 
to the student of snakes, and any one looking up anatomy of 
teeth ought to be referred to it, just as should any one seeking 
information about snakes. Therefore two cards are printed, 
with the numbers transposed. Thus one card has 81.2: 
14.31.4, and finds its way in sorting to “snakes”; the other 
has 14.31,4 : 81.2, and finds its way to “comparative 
anatomy, teeth.” 
Example 4:— 
Hall Ts. 47.1 Adeona: 14.99 
1897. On the occurrence of the Anchoring Tubes of Adeona 
in the Older Tertiaries of Victoria, with an account of their 
structure. Proc. R. Soc. Victoria N.S. Vol. 9, p. 1-4. 1 pl. 
To take a still more complicated instance (see Example 4), 
the above paper contains information which may be needed 
by the student of bryozoa, of comparative anatomy, of 
paleontology, and of geographical distribution. | Hence 
four cards are printed with the class numbers as follows :— 
(118): 47-1 Adeona. 
(94.5): 47-1 Adeona. 
14.99: 47.1 Adeona. 
47.1 Adeona: 14.99. 
