100 PLANARIA. 



it was only by taking advantage of their predilection for the light, which 

 attracted many to the side of a watch-glass, that an accurate drawing of 

 a group could be completed. Plate XV. fig. 1. In five days these ani- 

 mals were evidently farther advanced, though still furnishing a very 

 imperfect view, from altering their position, and tumbling over in the 

 water in an irregular manner. Now, however, they had about six marginal 

 fingers projecting, and these were completely bordered by active cilia. 

 The middle was of deeper red than previously ; and not very remote from 

 the centre, two dark specks like eyes, appeared on the upper surface, fig. 2. 



I could discover only two on June 3, which seemed to be unchanged. 

 All had disappeared on the 5th, on which day the parent also had perish- 

 ed from the excessive heat. 



From all these circumstances I was induced to conclude, that these 

 animals are the larvae which metamorphose to the Planaria cornnta. 

 But many parts remain for investigation, always difficult where the sub- 

 jects are either minute or rare. And we have already seen that it has 

 been impossible for us to follow the various stages of their development. 



From various other examples not so scrupulously investigated, the 

 spawn was apparently hatched in twelve or fourteen days, at which time 

 a multitude of animalcular specks swam amidst the water. 



The size and vigour of the parent decline after spawning, and the 

 colour fades to dingy white. 



The Horned Planaria lurks in the crevices of empty shells ; or, for 

 the most part, lies buried in mud, when recovered from the sea ; whence 

 it may be dislodged by imparting some impurity to the water. 



Specimens survive readily for a considerable time. Between forty 

 and fifty have afforded the substance of the preceding observations. 



PLATE XIV. 



FIG. 1. Planaria, cornuta, back. 



2. Belly. 



3. Specimen viewed from below, shewing the distribution of the inter- 



anea, enlarged. 



4. Spawn, enlarged. 



