Desoriptio7i of a 7icio species 



[No. 34, 



till it has descended to twice or thrice its own length, when the 

 thread attenuates and breaks, and the animal falls to the ground. On 

 meeting a smooth body, as a glass, &c., the lower surface of the 

 disc is applied to it like a sucker, and the animal draws itself up, 

 becoming thickened and corrugated by contraction, after which it dis- 

 engages the head and pushes itself forward. It is impatient of heat, 

 but not of light. When immersed in luke warm water it twists 

 about as if distressed. In cold water, although exhibiting no signs 

 of inconvenience, it always endeavoured to get out. When a bot- 

 tle, in which some of them were kept, was placed in the middle of 

 a basin of water to prevent their escape, they crawled out till they 

 encountered the surface of the fluid, which at first they seemed un- 

 willing to face ; but, at length, after many attempts, and much appa- 

 rent repugnance, some of the larger ones pushed forward their heads, 

 retaining their hold on the cork by the tail alone, until they touched 

 the edge of the basin on which the disc-like head was firmly fixed, and 

 the body was drawn after it. One of them getting disengaged before 

 it found the opposite side, tumbled about in the water as if helpless, 

 until it again reached the cork on which it seemed gladly to take re- 

 fuge, and returned to the bottle. Two or three others on finding the 

 bottom of the basin below the cork, crawled along it under the water, 

 appearing to find no difficulty as long as the abdominal muscle was 

 in contact with the Tessel. When imjuersed in cold water they in- 

 variably sought the surface of the bottle, crawling up the side, -and 

 clustering round the neck. 



Although easily injured, and susceptible of division by the use of 

 the slightest force, they are tenacious of life. When cut in two the 

 portions continue to live and move as if unhurt, and each fragment 

 would, doubtless, in time reproduce what was lost, so as to make a 

 perfect animal. The aquatic /??fmarz<5 are even said to reproduce their 

 species by spontaneous division, as well as by depositing their ova. 

 They seem to possess great powers of compression, effecting their 

 escape through the narrowest apertures. On one occasion several 

 of them, confined in a tumbler, contrived to squeeze themselves be- 

 tween the edge of the glass and the China plate on which it was placed. 



This species of Planaria may be characterised as follows : 



Planaria lunata f n. s.) 

 With a depressed, linear, opaque body dilating into a lunated disc 

 at the anterior extremity; having no perceptible organs, excepting 



