THE GIANT CHITON. 



Ill 



Fig. 99. 



nearly concealed them, bnt in this species the work is 

 completed. The whole back of the animal is cov- 

 ered with a hard, gritty, reddish brown mantle, which 

 wholly conceals the eight white valves, one of which 

 is shown in Fig. 99. 



These single valves are found much more often 



than the complete animal, 

 and from their peculiar 

 shape they are called But- 

 terfly shells. Perhaps 

 many who gather them 

 are at a loss to know their 

 origin, but a study of this 

 very singular ' ' butterfly' ' 

 of the sea will reveal all 

 the mystery. These 

 valves are pure white and 

 are about an inch and a half in breadth. 



In Fig. 99, we have the picture of a small speci- 

 men of the Black Chiton, Katherina tunicata, Sby. , 

 Kath-e-ri'-na tu-ni-ca'-ta, which was 

 named in honor of Lady Katharine 

 Douglass, who first sent a specimen to the 

 British Museum. The outline is ellipti- 

 cal, and the small white valves are nearly 

 covered by the thick black mantle. This 

 singular arrangement of the parts is so 

 striking that it cannot be mistaken for 

 any other species. Think of a smooth 

 Fig. 100. black skin, rounded like a whale's back, 

 and set with eight little shelly plates, and you will 

 get the idea. The foot is of a reddish color, and the 

 common length is two or three inches. It is especially 

 abundant far to the north. 



