CETACEA. 



69 



teeth of the Whale ; but this must be a mistake, for Mr. F. J. Knox 

 observes — " In the foetal B. Mystlcetus sixty to seventy dental pulps 

 were found on each side of each jaw, making the whole number 

 amount to from 260 to 300. The preparation (n. 56) exhibits a 

 portion of this gum with twelve pulps : had these pulps been con- 

 fined to the upper jaw and corresponded to the number of baleen 

 plates, it woidd have formed a strong analogy between the baleen 

 and teeth ; but the number of baleen plates in the Whale greatly 

 exceeds the number of dental pulps, and the lower jaw, which con- 

 tained an equal number of pulps with the upper, has neither teeth 

 nor baleen in the adult whale. Their presence therefore in the 

 foetal Mysticetus forms one of the most beautiful illustrations of the 

 unity of organization in the animal economy. The teeth in the 

 Balcena never cut the gum, but become gradually reabsorbed into the 

 system ; the very cavity in which the germs were lodged disappears ; 

 whilst, to suit the purposes of nature, the integumentary system 

 furnishes the baleen, which is evidently a modified form of hair 

 and cuticle." — Knox, Cat. Prep. Whale, 22. Professor Eschricht also 

 has shown that the foetus of Megaptera Boops (Danish Trans. 1845, 

 xi. t. 4) has numerous teeth on the edge of the jaw, though they are 

 never developed. I am inclined to regard the baleen as a peculiar de- 

 velopment of hair in the palates of these animals, and somewhat ana- 

 logous to the hair found in the palates of the genus Lepus. (See also 

 Romseau, Rev. Zool. 1856, 193, 257, 305, 353 ; Raimi, Ann. Set. Nat. 

 1836, 266 ; and Meyer, Nov. Act. Acad. Leop. N. C. 1855, xxv. 449.) 



From the examination I have been able to make of the baleen of 

 Balcenoptera rostrata, and of different masses of small blades of 

 Baloina australis, it would appear as if there were, at least in these 

 two species, two or more series of baleen on each side of the palate ; 

 the external series being formed of large triangular blades placed at 

 a certain distance apart ; and the internal, in BaJcenoptera rostrata, 

 composed of smaller, much thinner, triangular pieces, placed much 

 closer together, and forming a very dense screening-apparatus ; and 

 in Balcena australis the inner series is formed of numerous separate 

 narrow strips of whalebone, each ending in a pencil of hairs, which 

 vary in size from that of small twine to that of tape half an inch 

 wide ; these are placed behind the others, and gradually increase 

 in size from the innermost to the broad external series. They are 

 early deciduous, and the groove in which they are placed becomes 

 filled up and solid. 



Mr. Knox (Cat. Prep. Whale) gives the best account of the de- 

 velopment, position, and distinction between the baleen of the ^Tiales 

 of the North Sea which has come under my observation, and it agrees 

 with the observations I had made on the subject before I could pro- 

 cure his pamphlet. 



In Balcena maxbnus, Knox (Physalus antiquorum), 314 external 

 or labial plates (baleen) were counted on each side ; towards each 

 extremity these plates degenerate into bristles, and admit of being 

 counted with difficulty. Towards the mesial line the baleen as a 

 mass diminishes gradually in depth, giving the whole palatine surface 



