ox THK BILL OF THE HKROX. 125 



Plate XH. 



Paronella iusiffiiis (continued). 

 Fig. 81. The rig-ht foot of the third pair of legs, seen from the outer aspect. 

 82. The right mucro seen from the outer aspect. 



Sminthurides appendiculatus, sp. n. 



Fig. 83. The left antenna seen from the inner s'ide. 



84. The left hind foot, inner side. 



85. The left foot of the first pair of legs seen from the inner side. 



86. The right mucro seen from its outer aspect, if. i. ?., dorsal inner lamella; 



d.o. L, dorsal outer lamella; v. I., ventral lamella. 



Fseudocjjphodents annandalei, gen. et sp. n. 



Fig. 87. Foot of third pair of legs. 



88. Thcfuvcula viewed from the dorsal side, t.s., terminal scale. 



89. The left dens and mucro from the outer side. t. a., terminal scale. 



C'l/phoderus siinulans, sp. n. 



Fig. 90. The left foot of the second pair of legs. 

 91. The left mucro seen from its outer aspect. 



8. Ontogenetical Transt'onimtions of the Bill in the Heron 

 (Ardea cinerm.) By Prof. P. P. Sushkin, C'.M.Z.S., 

 Kharkov, Russia. 



[Received June 3, 1911 : Read November 7, 1911.1 

 (Plate Xlll.*) 



The birds of the subfamily Ardeinse are known to have a conical, 

 pointed, spear-shaped bill with a simple rhamphotheca. The 

 curious fact that these features are acquired only in a late 

 post-embryonic stage seems to have attracted little attention. I 

 have been able to trace a gradual development of these features 

 in a sei^ies of embryos and young Inrds of Ardea cinerea, 

 collected and generous}}^ presented to me l)y one of my friends, 

 Mr. J. G. Sobolev, of Moscow. 



In an embryo, in wliich the feather-papillae on the back have 

 just assumed a conical shape (length of the gape about 12 mm.), 

 the bill is straight and rather slender, the tip of the upper jaw 

 is conspicuously swollen (not only owing to the pi-esence of the 

 so-called egg-tooth), and the culmen is concave. ; a furrow runs 

 from the nostril to the base of the swollen tip (PI. XIII. fig. 1). 



In an embryo about one day before hatching (length of gape 

 22 mm.) the for-m of the bill has already changed ; it is thicker, 

 its swollen tip is not so prominent and is slightly hooked, and the 

 culmen is not so concave. The horny sheath of the bill is mani- 

 festing itself ; the covering of the tijis of both jaws is thicker and 

 more solid, and the covering of the tip of the upper jaw is marked 

 off by a raised ai-ea ; a furrow anterior to the. nostril, and a space 



* For e\]il:tnation of the Plate ^ee p. 126. 



