PLANARIA NIGRA. 25 



lower down than the middle of the body, 

 and the second still nearer the extremity 

 of the tail. The opacity of the animal 

 precludes us from accurately distinguish- 

 ing its internal organization ; nevertheless, 

 enough may be discovered to infer, that it 

 is far from simple. Among black Planarise, 

 some occasionally occur of the ordinary size, 

 figure, and proportions, but, instead of the 

 jetty colour proper to the species, they 

 are of a dark grey. By interposing them 

 between the eye and concentrated rays of 

 light, the internal structure may be ob- 

 scurely recognized in many vessels, branch- 

 ing from about the middle of the body, and 

 terminating in obtuse extremities near the 

 margin. These are certainly analogous to 

 the pinnate ramifications already descri- 

 bed ; and they bear much resemblance to 

 the viscera of leeches. Facts do not war- 

 rant our concluding that the grey Planarise 

 are indubitably a different species, or that 

 they are only varieties ; their contour seems 

 more ovate, indeed^ and they are seldom if 



