OCR Text |
Show 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 characters of the nose-pad are preserved, the skull is available for examination if necessary, and the collector is saved the trouble and expense incidental 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 comparison of the basal length, interorbital breadth, and "lobe-measurement " 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 pf is the distance in a straight anteroposterior 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 satisfactorily 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 premaxillae). The fairly constant "interorbital" must not be confused with the varying and changeable " intertemporal " breadth. Lobe- Basal Interorbital measurement length. breadth. of p.4 Lutra brasiliensis, $ 141*5 18*0 16*1 ,, cupensis (<S) 129 32*5 13*8 „ (?) 118 26*4 14*0 ,, barang, S 118 26*5 12*7 „ ' (?) 108*5 20*8 11*8 „ vulgaris, 6 114 225 8*8 ,, (?) 104*8 19*8 8*4 ,, sumatrana ( S) ..... .(c.) 112 18-81 9*2 2 (c) 98 15*2 8*5 „ canadensis, rf 101*5 24*5 10*1 ,, paranensis **• 97 22*5 9*8 ,, maculicollis, cS 96*2 15*5 8*9 „ felina, d 80*3 200 10*0 $ 84*2 21*8 8*6 „ cinerea, cS 82*2 205 y*0 $ (c.) 82-0 18*0 9*5 1 The sex-mark is here, as elsewhere, placed within brackets where the is only presumed from the form or relative size of the skull, and is not known from external or historical evidence. 2 From the type specimen of L. jilatensis, Waterh. |