2 ARKIV FÖR ZOOLOGI. BAND 8. NIO 10. 



thick. At the first glance the skin very muck resembles that 

 of a porpoise. There is therefore no wonder, tbat many 

 earlier anatomists have noticed it, e. g. Goodsir (1841), Cle- 

 land (1862), Turner (1862), Harting (1865), Wahlgren 

 (1868), Lutken and Steenstrup (1898). We owe our pre- 

 sent knowledge about the strncture of the integument of the 

 Molids mainly to Turner, wo has given an account thereof 

 which must be considered an excellent one for that time. He 

 found by chemical investigations, that the white mäss con- 

 tains no oil, but solely connective tissue without any elastic 

 fibres. He described the tubercular plates. They consist 

 according to him of two parts of distinctive microscopic 

 characters. He made also some remarks on the development 

 of these plates. That he made some mistakes at a time when 

 very primitive microscopic methods were in use, will not cause 

 any surprise. Turner has described a cuticle covering the 

 superficial surface of the tubercles. An examination of the 

 microsections which I have made through the skin of a Mola 

 shows at once, that the plates are covered by two layers of 

 quite different tissues, the epidermis and a layer of loose 

 connective tissue. I have studied the integument of both 

 full grown specimens and of young ones of a length from 1,5 

 to 5 mm., the results of which I shall give below. 



Epidermis. No remarks on the epidermis of the Mola 

 have been made hitherto in the literature. This is very 

 thick consisting of a great number of layers of cells. The 

 cells are of two kinds, indifferent epithelial and mucous. The 

 latter are large and form the greatest part of the epidermis. 

 The indifferent cells occur partly along the base of the epi- 

 dermis, partly between the mucous cells. In microscopic 

 slides stained with Bismarckbrown and Indigo-carmine this 

 difference is rather conspicuous. The indifferent cells (stained 

 with Indigo-carmine) form a kind of network, so to speak, the 

 meshes of which are filled up by the mucous cells (stained 

 with Bismarckbrown). No »Kolben »cells are to be found. 

 Owing to the enormous development of the mucous cells the 

 epidermis gets quite a slimy consistence. A very distinct 

 limit between the epidermis and the corium is formed by a 

 basal membrane. (Fig. 1.) 



Corium (Fig. 1 and 2). The corium consists of two 

 distinct layers, one exteriör and one interiör. The exteriör 



