96' DR. THOMAS ALCOCK ON THE 



scarcely visible. In the axilla on the right side were 

 three distinct rows of short round-ended processes of equal 

 length, which were evidently the internal gills. They 

 were placed in a deep depression behind the roots of the 

 plume-gills. On the left side, in the same position, 

 there was a cluster of short processes of equal length and 

 similar in character to those on the right side ; but showing 

 more a side view, their arrangement in rows did not appear. 



21. A drawing was made of a tadpole, the natural size. 



21 (2). It was then killed and examined under the 

 microscope. A drawing was made of the under surface, 

 which showed the suckers diminished in size, the opercular 

 fold meeting across the chest, and a deep depression in 

 each side at the root of the plume-gills. These were 

 diminished in size ; but the circulation was still seen in 

 them. 



Plate VII. 



22nd. A tadpole was killed and examined. The appear- 

 ances being exactly the same as those represented in the 

 drawing made on the 21st day, except that the suckers 

 were very slightly smaller, a fresh drawing was not made. 



At this time the stock of tadpoles in the basin failed : 

 all that remained in it died, apparently in consequence of 

 the water becoming putrid after one or two dead leaves 

 from the pond had been put into it. The spawn which I 

 received at first was a large mass about a foot in diameter ; 

 and the whole of it, except the small quantity already 

 mentioned as kept in the house, was placed in an artificial 

 pond in my garden. The pond is 16 yards long, and 9 

 yards across at the widest part, it is lined throughout with 

 Portland cement, and is about 2 feet deep. 



This spawn remained among some dead leaves in a shal- 

 low part where it could be easily seen. It was looked at 



