﻿6 ARKIV FÖR ZOOLOGI. BAND 4. NlO 12. 



The forehead as well is very different. The interorbital 

 space is much broader (see table of measurements) in the 

 true Lutra capensis, but nevertheless it is not only compara- 

 tively but even absolutely shorter than in L. c. hindei: 

 breadth and length being in the former resp. 36 and 15 mm. 

 and in the latter 28,5 and 17 mm. 



In L. c. hindei the zygomatic arch is much more slender 

 (see table of measurements) and foramen infraorbitale is abso- 

 lutely larger than in the true Lutra capensis, the difference 

 being 1 or 2 mm. in each direction. There are other fora- 

 mina as well which are larger in the smaller form. This is 

 for instance the ca se with foramen lacerum posticum which is 

 longer and larger in the Rhodesia otter. This stånds in con- 

 nection with the comparatively greater thinness of all bones 

 in the skull of the latter. 



With regard to the mandible there is a corresponding 

 difference to be seen, as may be expected. Every part of the 

 mandible of the true L. capensis is more massive. The trans- 

 versal length of the condyle is 27 mm. and the vertical dia- 

 meter of the inner half is 8 mm., while the corresponding 

 measurements of L. capensis hindei are resp. 24,5 and 6 mm. 

 Still more striking is the enlargement of the lateral flange in 

 the angular portion of the mandible in the typical L. capensis, 

 in which the greatest width of the under surface of the man- 

 dible (vertically beiow processus coronoideus) measures 15 mm., 

 while the same measurement in L. c. hindei from Rhodesia 

 is only 11 mm. The greatest thickness oi processus coronoid- 

 eus and the greatest width of its anterior surface is in the 

 latter only 3 mm. but in the former 5,5 mm. The vertical 

 height of the mandibular ramus below the middle of m^ is 

 in the latter about 17 in the former 21,5 mm. 



The size of the teeth, especially the last upper premoJar 

 and the molars of both jaws is also very different as is proved 

 by the table of measurements, and the figures show that the 

 shape of these teeth likewise is different (conf. the plate). 



The structural difference of the skull of the true L. ca- 

 pensis from that of the Clawless otter of Rhodesia lies, — 

 as may be concluded from this description, from the measure- 

 ments and from the figures, although all details have not 

 been entered upon, — to a great extent in the enlargement in 

 the former of processes, crests, grooves etc. which serve for 



