KUNG],. SV. VET. AKADEMIENS HANDLINGAR. BAND 40. NiO 5. 47 



hinted at, partly because no Coronulce are present in the »bonnet» and partly be- 

 cause the »bonnet» is developed already in the uterine foetus. If an explanation 

 shall be tried, there are two things which ought to be explained, the origin and the 

 function. With regard to the origin, it lies near at hand to compare the serially 

 arranged excrescenses of the upper as well as the lower jaw of Balcena australis with 

 the tubercles of Megaptera which have a similar situation and, at least in the foetal 

 stage a similar appearance. As the tubercles of Megaptera carry hairs, at least in the 

 foetus, they have above been regarded to be, at least from the beginning, footstalls 

 of vibrissa?. From such an origin the tubercles might have become enlarged when 

 their function was altered. Megaptera carries a cluster of tubercles at the eud of 

 the lower jaw. The large excrescences at the endof the mandible of Bålarna australis 

 might correspond to such dusters which secondarily when enlarged have become 

 united. And perhaps the »bonnet» has originated in a similar way. If this explana- 

 tion as to the origin is correct it remains to guess what function these organs may 

 have now, because they cannot be sensory organs with such a structure, that is 

 quite impossible. As the »lice» in väst amounts cover these excrescences, it lies near 

 at hand to guess that there is some important connection between the excrescences 

 and the Cyami. It has already been proved that the former cannot be entirely 

 pathological products caused by the latter, but the rugged surface might be the result 

 of the irritation of the epizoa which could have caused hypertrophy of the epithelial 

 layers of the tubercles. On the other hand, the question offers itself: »Are the 

 Cyami really parasites and in what respect and to what extent can they be such. » 

 The Cyami have not a suctorial mouth as would be expected of parasites. They 

 have no organs with which they could bore through the thick and solid epiderm of 

 the Black whale — which in the samples of skin preserved by Sörling has a thick- 

 ness of about 8 mm. — for the purpose of suckiug the blood of their höst. What 

 harm can they then do ? If they should gnaw themselves through the epiderm there 

 ought to be wound and scars. But there are none such. Perhaps the Cyami are 

 then only harmless scavengers which feed on the natural offal of the skin of their 

 big höst and, perhaps, they might even be useful to him. This usefulness might 

 then consist therein that they kept his skin clean, and, especially, that they de- 

 livered him from larvae of Cirripeds which otherwise might attach themselves to 

 the skin of the whale and then grow out to great masses which gradually could be 

 large enough to hinder his free movements and progress through the water. It is 

 well known in which a high degree ships might be impeded in their speed by cirri- 

 peds, and it is also well known that barnacles, especially Coronulce, fix themselves on 

 whales and then secondarily Ohonchoderrns on the shells of the barnacles. If the 

 Cyami should really be able to prevent that, they would, certainly, be of great ser- 

 vice to the whales, and it would be well if the latter could offer places where their 

 not parasitic but usefully symbiotic Cyami could be protected. It might therefore 

 be put up as a hypothese that the excrescences spöken of above have been second- 

 arily adapted to be domicilia for the Cyami. 



This is a daring hypothese as to the function of the tubercles and excrescences 



