1894.] TADPOLE OF XENOPTJS L^TIS. 103 



the latter animal this constriction is due to a bulging of the body- 

 in the region of the pronephros. This bulging is less marked in 

 the tadpoles of Xenopus. The dorsal fin commences just before 

 the median occipital elevation begins to slope away posteriorly ; 

 the ventral fin commences just in front of the accurately median 

 anus. The " abdomen " ha,s a metallic glitter, and becomes much 

 more swollen and relatively shorter in the later stages. The fins 

 are continuous to the very end of the tail ; there is no " Chimseroid 

 lash " as depicted by Parker \ 



Habits. — The tadpoles generally rested in the water with the 

 head downwards and the tail in constant wriggling motion. 

 Whether this is connected with respiration or not I am unable to 

 say. In any case I detected no special vascular supply or mechanism 

 of any kind which might be related to such a function. 



The food of the tadpoles consisted entirely of Cyprids, with 

 which the tank, where they were housed, swarmed. Their in- 

 testines were invariably full of these Crustaceans and of nothing 

 else. In spite of their purely carnivorous diet, the intestine was 

 just as much coiled as in the common tadpole. The carnivorous 

 diet, it should be remarked, was adopted from choice and not 

 from necessity. There was plenty of water-weed upon which they 

 could have fed. It is generally stated that the tadpole of the 

 Common Frog is a vegetarian. It will, however, eat animal food, 

 such as the dead bodies of its companions ; it can also be compelled 

 to take to a purely carnivorous regimen. 



The following is a brief statement of the measurements and 

 general characters of tadpoles at various stages. 



Stage I. 



Four specimens of the first stage were preserved in Perenyi fluid 

 at 10 A.M. on May 29, i. e. 12 to 15 hours after hatching. 



The total length of the tadpoles is after preservation 5 millim. 

 Corresponding to tadpoles of same lengths figured by Marshall and 

 Bles. 



Stage II. 



Preserved at 12 midday on May 30. Three individuals as 

 nearly as possible of the same length, {. e. 7 millim. Corresponding 

 more or less to 9 millim. in tadpole figured by Marshall and Bles. 

 The relative proportions of body to tail are 2 : 3. 



Stage III. 



Preserved on June 1st. Length 8 millim. The form of the 

 "adult" tadpole fully established. Length of body to that of 

 tail as 3 : 5 ^. 



^ The appearance occurs, however, in spirit-specimens, owing to the clinging 

 of the membranous fins to the solid part of the tail. 



^ The measurement of the body is taken to end of swollen abdomen, not to 

 anus. 



