Family PANURIDAE. 

 Panurus biarmicus (L.) — Bearded Titmouse. 



(Plate 45, fig. a-c). 

 (Snouckaert: Avifauna Neerlandica, p. 32, No. 74). 



Colour of surface of shell: 

 Colour of spots: 



Average dimensions: 

 Average weight of shell: 

 Texture of shell: 



Shape : 



Nest; 



Site of nest: 



Number of eggs: 

 Breeding season: 

 Duration of incubation: 



milk-white; sometimes strongly inclined to 

 greyish yellow; rarely lime-white. 



small dull brown or blackish brown lines 

 and curls. In the eggs examined by me 

 down to the inner membrane, I have not 

 found the grey or greyish red speckles 

 which are said by Thienemann to occur 

 in the deeper layers of the shell. 



17.22 X 13.91 millimetres. 



0.11 gram. 



a granulation of an entirely different nature 

 to that of Paridae-eggs, and standing by 

 itself in this respect also. 



compact; when cut transversely unequal 

 halves are produced. 



chiefly 



is built of withered parts of plants; c 

 of portions of reeds and reed-grass. 



close to the ground, between reeds or reed- 

 grass, stinging-nettles, etc., in the midst 

 of extensive reed and willow vegetation. 



5-7 (after-set: 4-6). 



end of April— July. 



about 13 days. 



Remarks : Oologically biarmicus stands quite by itself. Upon examining the various layers of 

 the eggshell of this species 1 ascertained, among other matters, that only the surface of the 

 upper layer bears spots; in the deeper layers (v. supra) I found no pigment. A deposit of 

 pigment similar to that occurring on biarmicus-eggs, which 1 have found on the deeper and 

 deepest layers of eggshells, for instance of Corvidae and Falconidae, and — but almost 

 hidden to the naked eye — between and immediately under the coarser spots or cloudy 

 markings in the higher layers of several Passeres-eggs, 1 consider to be a very original 

 marking; with some species it still occurs on the surface as the typical marking, with others 

 only as an exceptional one; in the latter case it frequently occurs that fewer layers of car- 

 bonate of lime have been deposited than normally takes place. 



