SYLVIIDAE. 



CALAMODUS AQUATICA (Gmelin). 



This species, which selects extensive marshes by preference for its 

 home, undoubtedly formerly existed in large numbers locally in the 

 Netherlands as a breeding bird, as was the case with Loc. luscinioides 

 also. Thienemann received several nests in the years 1845 — 1856 

 from the environs of Rotterdam (through the intermediary of a 

 Mr. Lobbecke). 



ACROCEPHALUS STREPERA (Vieillot). 



Naumann mentions the occasional occurrence of eggs which are 

 aberrant in shape as well as in marking, and which are described 

 as follows : ,, elongated ovoidal ; dirty white (brownish rather than 

 „greenish) ground colour; marked with many dirty brown (rarely 

 „ashgrey as well) speckles and similar (only darker) large spots at 

 „the thicker end, which frequently form a very broad ring covering the 

 „ground colour of the basal portion of the eggshell. Intermediate forms 

 „between this aberration and the ordinary type are unknown". Judg- 

 ing from the description — leaving the shape out of consideration — 

 fig. 20 of Plate VIII in Part IV of the „Catalogue of the Collection 

 of Birds' Eggs in the British Museum" shows such a strepera-egg; 

 it reminds one most of one of the rarer egg-types of S. svlvia and 

 of a certain variety of simplex-eggs, of which, curiously enough, 

 specimina are shown on the same plate (fig. 11 and 13). Thiene- 

 mann held strepera and palustris to be one species, frequently pas- 

 sing, oologically as well, into each other ; although in the system 

 they are now separated as two so-called good species, I nevertheless 

 consider — on the ground of what is subjoined — that it is wrongly 

 attributed to a confounding of the eggs of one species with those of the 

 otherwhere the said author says ofasetofsfr^ra-eggsthat in character 



