171 



KEY TO MARINE MAMMALS (Cont.) 



29 Rostrum straight, long and slender, transverse width in the middle 

 of the rostrum not more than one-seventh of its length; one tooth 

 on each side of lower jaw, erupted or hidden beneath the gum, set 

 quite far to the rear of the fore-end of the lower jaw, usually 

 behind the tip of the rostrum when the mouth is closed; teeth 

 laterally compressed, their anterior-posterior axis at least 

 twice as long as transverse axis. 



BEAKED WHALES (4 species; skull needed for identification) 



29' Rostrum not as above, width in middle not less than one-sixth of its 

 length; one or two teeth in each side of the lower jaw (erupted or 

 hidden beneath the gum), usually set at tip and in front of the 

 upper jaw tip when mouth closed; teeth nearly round in cross section, if 

 flattened, then anterior-posterior axis not more than 1.5 times the 

 transverse axis. 30 



30 Two teeth in each side of lower jaw; well developed grooves in front 

 of eyes (preorbital ) , sharply defining rear margin of rostrum; rostrum 

 in dorsal view, narrow at base, the length being 2.0-2.2 times the 

 width between the grooves; forehead not concave in front of blowhole; 

 distinct beak and bulging forehead present; beak flattened dorso- 

 ventrally, its margins parallel to one another. 



BOTTLENOSE WHALES (skull needed for species identification) 



30' One tooth in each side of lower jaw; preorbital grooves not sharply 

 defined; rostrum in dorsal view relatively shorter and wider than 

 above, forming more closely an equilateral triangle; forehead slightly 

 concave in front of blowhole, increasing in concavity with increasing 

 size; no distinct beak or bulging forehead; beak not flattened dorso- 

 ventrally, its margins not parallel. 



GOOSE-BEAKED WHALE 



31 No dorsal fin, but rather a low, narrow ridge near midpoint of back; 

 either one pair of teeth in upper jaw (in females (Fig. 37), usually 

 concealed beneath gums and sometimes a tusk; in males, a tusk up to 

 3 m in length), OR up to 44 teeth (8-11 pairs above and below), the 

 upper teeth markedly inclined forward and usually having an egg-shaped 

 cavity on the lower edge of the crown, produced from friction with 



the anterior lower teeth. 32 



31' Dorsal fin present or absent (if absent, then total tooth count not 



less than 60); lower jaws always with teeth. 33 



32 Same color all over (adults white or yellowish; young 1.5-2 m long, 

 slate gray or brownish); 32-44 teeth (8-11 pairs above and below), 

 teeth set widely apart, inclined markedly forward in upper jaw; 

 distinct neck constriction behind head. BELUGA OR WHITE WHALE 



