ON EXPERIMEXTAIi PHEASANT-BREEDHSTG. 539 



ioining, the upper part of the valve being solid and projecting 

 freely, while the carina of S. fossida has the intrapai-ietes 

 forming a thin wall on each side of the carina, which is a more 

 advanced tj^pe. There is not as yet sufficient evidence to prove 

 whether *S'. fossula was derived from 6'. arciudum or not. It is 

 patent, however, that from the foregoing species subsequently 

 arose the forms grouped as Arcosc(dpeUuvi and characterized by a 

 reduction in the number of plates of the capitulum, by a sup- 

 pression of the rostrum, and a tendency towards the reduction 

 of the pair of infra-median latera. 



For help in connexion with this paper I wish to express my 

 indebtedness to Dr. F. A. Bather, Dr. W. T. Caiman, Mr. 0. P. 

 Chatwin, and Dr. P. P. 0. Hoek. 



Key to /Sjjecies ^mentioned. 



A. Carina without intvaparietes, parietes not 



reacliing to the basal margin and bent almost 



at right angles to the tectum S. simplex Darwin. 



B. Carina with intraparietes bent inwards and 



joining, the upper part of the valve solid and 

 projecting f'reelj\ 



1. Carina with basal margin rounded S. accunmlatum Withers. 



2. Carina with tectum tlatly-arched transversely, 



and marked with numerous fine longi- 

 tudinal ridges S. arcuatum Darwin. 



3. Carina with tectum tlatly-arched transversely, 



and marked with three prominent longi- 

 tudinal ridges, one central, and one on 

 either side separating the tectum from the 

 parietes_ S. trilineatum Darwin. 



4. Carina with tectum strongly convex trans- 



versely and marked with several longitudinal 



ridges ^ S. solidulum Steenstrup sp. 



5. Carina with tectum strongly convex trans- 



versely with smooth surface S. maximum var. cylindra- 



C. Carina with intraparietes forming a thin wall [ceum Darwin. 



on each side of the valve. 



1. Carina with tectum and parietes smooth, 



dorsal surface and iimer margin much 



arcuated S. hastatum Darwin. 



2. Carina with tectum bordered on each side by 



a large, protuberant, flat-topped ridge S. fossida Duxvi'm. 



2di. Experimental Pheasant-hreedino-, 

 By Rose Haig Thomas, F.Z.S. 



[Received December 4, 1911 ; Read February 6, 1912.J 



(Plates LXiy.-LXVII.*) 



The expei'iment with which I deal in this paper was under- 

 taken to test the truth of the result of one previously made 

 (P. Z. S. 1909, pp. 884-885), in which it was shown that a male 

 Pheasant had transmitted to his female oifspring of the second 



* For explanation of the Pktps see p. 545, 



3G* 



