200 ON THE DIFFERENT SPECIES OF OTTER. [Apr. 2, 
that one of the best and most convenient methods of preserving 
Otters for scientific purposes is simply by cutting off their heads 
and putting these into spirit. By this means the eharacters of the 
nose-pad are preserved, the skull is available for examination if 
necessary, and the collector is saved the trouble and expense inci- 
dental to skinning or sending home the whole animal. Where this is 
done, however, the sex of each individual should be carefully noted, 
and marked on a label attached to the head. 
Finally it may be of use to give a few of the more diagnostic 
cranial measurements of the Otters above recognized, since a com- 
parison of the basal length, interorbital breadth, and ‘‘lobe-measure- 
ment’? will enable students in most cases to recognize the species 
from these few dimensions only. The species are here arranged in 
order of size, based upon the basal length. 
The “lobe-measurement ” of p.* is the distance in a straight antero- 
posterior line from the most anterior point of the tooth to the most 
posterior point of the hinder convex edge of its inner lobe. This 
measurement includes, it is true, a part of the tooth not belonging 
to the inner lobe, but there appears to be no other way of satisfac- 
torily estimating the size of the lobe. The “basal length” is of 
course from the basion (back of the basioccipital in the median 
line) to the gnathion (most anterior point of the premaxille). The 
fairly constant ‘‘ interorbital’’ must not be confused with the varying 
and changeable ‘‘ intertemporal ”’ breadth. 
Lobe- 
Basal Interorbital measurement 
length. breadth. of p.t 
Lutra brasiliensis, Q ........ 141°5 18-0 1671 
Hy, MCHPOHSIR (SP mae, @ als eae 129 O20 13°8 
f Fh Go) Mead ee 118 26°4 14-0 
Sh, UOT ONG AM Omae ote cecke 7 oS 26°5 12°7 
“s hg Ae eee edt chem cen 108°5 20°8 11°8 
Pb fC LL Ph il on aah 114 22°5 8:8 
7 RR <i eA ata 1048 198 8-4 
», sumatrana(d)...... (ey 1t2 18:8? 9:2 
. : tees le). 48 15-2 8:5 
san COMAMETSIS 1G) pawas-uegtiaie, oie 101°5 24°5 10°1 
55ers SIGE GULISIS i arte dara, a alteeisaieis 97 2225 9:8 
sac) SNACULICOULUS Ss Gama ree 96:2 15°5 8:9 
Pg 1 AM ier peck Pec 80°3 20°0 10-0 
ts ‘ Rea ety Sensteuta aid &4°2 21°8 8°6 
eae CINCTEG TC « cusdeimecut Goin 82°2 20°5 9-0 
5 3 Otaniemi ate (c.) 82:0 18:0 9°5 
1 The sex-mark is here, as elsewhere, placed within brackets where the sex 
is only presumed from the form or relative size of the skull, and is not known 
from external or historical evidence. 
? From the type specimen of L. platensis, Waterh. 
