72 ME. SWALE VINCENT ON THE 



centre (PI. XIV. fig. 46, csp.). This appearance is described a,bove, and some expla- 

 nation of it has been ofiered. The alveolar walls are permeated by capillary blood- 

 vessels (PI. XIV. fig. 46, ca2}.). 



In the Pleuronectidge the appearance under a low power is very like that of a 

 lymphatic gland, but under a high power an alveolar arrangement can always be seen, 

 and the nuclei are seen to belong to more or less closely-packed cells of the two 

 vai'ieties described above. In Fleuronectes limanda distinct acini are often seen almost 

 like those of the mammalian pancreas, filled with cells of spindle-shape, with large round 

 nuclei and very distinct nuclear figures. There is a tendency towards a clear space in 

 the central part of each. In Bhoinbus Iwvis the acini are quite filled with cells, which 

 are more rounded than in other members of this family, and there is generally more 

 cell-protoplasm. 



In the Gadidae the individual members do not differ very widely from each other. 

 In Gadus morrhua the cells are pear-shaped, oval, rounded or irregular, and in the 

 specimens I have examined nearly all have large round figured nuclei. In Gadus 

 eeglefinus the appearance is peculiar: the acini appear to be occupied by scarcely 

 anything more than free nuclei with nuclear figures, the cell-protoplasm being scanty 

 and irregularly branched. Molva vulgaris shows the acinar arrangement very well, 

 with a very regular ring of nuclei round the outside of each alveolus. 



PI. XIV. fig. 47 represents the appearances in the suprarenal of the Wolf-fish 

 (Anarrhichas hqms). The alveoli are elongated, and there is an incomplete central 

 space (PI. XIV. fig. 47, c.sp.). Thus it is possible to consider that there are two chief 

 types in the alveolar arrangements of teleostean suprarenals : one, as in the Mursenidse, 

 is not unremindful of the testis in some animals {cf. Mihalkovics, 14), while the other 

 is more suggestive of the mammalian pancreas. 



The suprarenals of the Sunfish {Orthagoriscus inola) have a very peculiar structure, 

 in that the acini are very long and tubular. 



4. DIPNOI. 



In Protopterus annectens, Parker (17) describes "around the kidney, but more parti- 

 cularly along its dorsal and outer sides, masses of brown cells, which in appearance 

 remind one of the adrenal bodies of Amphibia," and he suggests the enquiry " whether 

 they or the lymphoid cells which give rise to them have anything to do with the 

 adrenals." 



I have examined this point with some care, and I have been able to verify in every 

 detail Parker's account of this lymphoid tissue, both round the kidneys and along the 

 alimentary canal, and forming the substance of the spleen. This I was enabled to do 

 by means of two specimens of Protopterus which Prof. Parker was kind enough to 

 send me. 



By the kindness of Prof. Bridge, I have also been able to examine the kidneys and 



