RIGHT WHALES 213 



whalers called it the Sarde, and in Icelandic the Sletbag was 

 the name given to it. 



The features distinguishing the Black Right Whale from 

 the Greenland Right are not very conspicuous ones. The 

 general external appearance is the same in both species, and 

 it is only in detail that any difference can be detected. The 

 colour, of course, is usually indicative, and the absence of a 

 white patch on the anterior end of the lower jaw means that 

 the animal is other than a Greenland Right Whale. But 

 although the other species is generally black all over, patches 

 of white may occasionally be distributed quite irregularly on 

 the under surface of the body. White spots, too, are some- 

 times found, due to the alteration of the skin produced by 

 parasites. 



The head of the Black Right Whale is shorter than that of 

 the Greenland Right, being only about one-quarter of the 

 body-length as compared with one-third in the latter species. 

 The arching of the upper jaw, or crown, is not so pronounced 

 as in the Greenland Whale, so that when viewed laterally the 

 outline of the head passes evenly backwards into that of the 

 body. The outline of the lower jaw is somewhat different 

 from that of the Greenland Whale. The whalebone, although 

 still much longer than in any of the Rorquals, is on the average 

 a foot or two shorter in the Black Right Whale than in the 

 Greenland Right. 



There is commonly developed on the front portion of the 

 upper jaw a horny excrescence known as " the bonnet ". 

 It is irregular in shape and infested by parasitic worms and 

 crustaceans ; its length is about n inches and its width 8 

 inches. The function of this protuberance, which has been 

 compared to the horn of the rhinoceros, is unknown. Beddard, 

 in his ' Book of Whales ', says that it " gives one the impression 

 that it is a pathological structure, a kind of corn, perhaps 

 produced by the animal rubbing itself against rocks as this 

 species has been observed to do to get rid of the barnacles 

 which are apt to infest it ". The presence of parasitic 

 barnacles is in itself almost a diagnostic feature of the species, 

 for they are never known to occur in the Greenland Right 

 Whale. 



In the absence of dorsal fin and of grooving on the throat 



