KUNGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 40. NIO 5. 



45 



the epithelial layers have been built up, so to say, round the long and slender pa- 

 pilla? it follows that even the epithelium on top of the papillary layer has a kind of 

 fibrovis texture. This has also been stated by Ridewood who has made a micro- 

 scopic examination 1 of the strueture of the »bonnet». The long papilhe, and the, by 

 them produced, fibrous texture of the epithelial layers constitute nothing stränge or 

 aberrant in themselves. Similar structures are found a little everywhere in the mam- 

 malian series, in such cases when thick epithelial resp. horny layers must be produ- 

 ced. The long papilke from the cutis are necessary as well for nourishing the epi- 

 thelial strata during their luxurious growth as for the sake of firmly attaching the 

 epithelial organ, what it may be, a horn, a hoof etc, to the underlying cutis. And 

 the fibrous texture of the epithelial derivates is simply, as already stated, a neces- 

 sary result of the mode in which the growth has taken place round the nourishing 

 centres which the papillse con- 

 stitute. But if, so far, the »bon- 

 net» does not exhibit any pecu- 

 liarities, its exteriör shape and 

 strueture are very stränge, and 

 at the same time its possible 

 function and the cause of its 

 existence are very mysterious. 

 As is elucidated by the figures 

 44 on Pl. X and 45 on Pl. XI 

 the »bonnet» has a very rugged 

 surface. It is deeply pitted and 

 honeycombed, and the pits and 

 holes are very irregular with 

 regard to size, shape and depth. pj g 5 Diagrammatic sketch to show the arrangemeht of the ex- 

 In the living animal these holes crescenses of the head of the southern Black whale. 



are filled with, and the whole 



»bonnet» covered by a immense crawling mäss of countless numbers of »lice», that 

 is Cyami. In the photographed specimen most of them have been shaken off to 

 allow the strueture of the organ to be visible, but many remain, as can be seen. 

 There are, however, no other parasites to be seen besides the Cyami. 



Behind the »bonnet» sits on the upper jaw a series of a good deal smaller 

 excrescences arranged on either side as the accompanying diagrammatic sketch (made 

 by Sörling at South Georgia) shows. In the original to the sketch these excrescen- 

 ces were five in Jiumber. One of them was cut out by Sörling and preserved and 

 has been reproduced photographically Pl. XI fig. 46. The actual diameters of this 

 sample piece are resp. 17 and 12 cm. As was the case with the »bonnet» great 

 masses of Cyami cover this excrescence as well. But in addition to them the smaller 

 maxillary excrescences contain a kind of barnacles which are quite deeply sunk into 



1 Proc. Zool. Soc. London 1901 p. 44. 



