tgii. Lindner — tnnimous Owls. 53 



on those which are not always immersed, belongs un- 

 doubtedly to the Cblorosperma and to the order Ulvaceae. 

 Under the microscope it is recognised as consisting of 

 colourless thallus or phycoma, which is transparent, com- 

 pact, and sharply defined. It is composed of cellular 

 tissue, the interior substance of which consists of cells full 

 of endochrome-green ; they are small, angular, often 

 standing together in fours and lodged in different strata 

 of unequal depth. This phycoma hangs by simple aggre- 

 gation on tlie surface of the vanes of the quills, which it 

 overspreads without any change h)eing evident. And just 

 as Ulvae grow on other algae, from which they probably 

 do not suck food, but in which they, as pseudo -parasites, 

 find conditions (or local fixation, so the present Ulva is 

 attached, as a pseudo-parasite, to those feathers which 

 are exposed to the air and sea water by turns. If the Ulva 

 should be new, I propose the name involvens for it.' 



" Confirming this statement, I can add that I have 

 never seen this alga on the feathers of the under surface 

 of the body, but always above, and especially on the tail- 

 quills, on the pinions, and on the shoulders. It is attached 

 only to the edge of some feathers, while the middle part, 

 covered by the overlying feather, is free. I have also 

 observed this alga exclusively on yoimg birds, and I have 

 never seen it on the feathers of adults." 



Being convinced that the remarks made about the 

 " luminous owls " are not at all due to an illusion, but to a 

 reality, I think that the appearance may probably be 

 caused by a local micro-organism. Therefore, I propose 

 to continue my observations with regard to " luminous 

 owls " on these lines. 



Wettenburg, Saxony. 



