THE TONGUE SHELL. 215 



Within the valves are singular shelly loops for sus- 

 taining the organs. 



Waldheimia Gray/, Davidson, has quite thick, red 

 valves, marked by eight or ten radiating ribs. The 

 shells are rather flat, somewhat triangular, and are an 

 inch and a half or less in length. 



Our last engraving, Fig. 182, gives us a represen- 

 tation of Lingula albida, Hds., Iyin'-gu-la al'-bi-da. 

 The shell is shaped like a duck's bill, being 

 thin, with nearly straight edges and a square 

 end. It fastens itself to an anchorage by a 

 long, fleshy stalk, which is shown in the cut 

 as dry and curled. The shell is glossy, and 

 is of a yellowish white color. It is a southern 

 species, and is about an inch in length. 



Besides all these, there is another class of 

 Fig. 1S2. mollusks, which are the most highly organized 

 of all. They are the Cephalopods or Head-walkers, 

 so named because they have a series of large tentacles 

 around the head, and these they use both for locomo- 

 tion and for prehension. They include Squids, Cuttle- 

 fishes, and Nautili, the last of which alone have true 

 external shells. Octopus punctatus, Gabb, Oc'-to- 

 pus punk-ta'-tus, is the eight-armed Cuttle or Devil- 

 fish which is chiefly found in southern waters. It has 

 power to change its color, but it is generally of a dark 

 hue, marked with many small dots. 



There are several species of Squid along the coast, 

 the names of which seem at present to be rather 

 uncertain. They have long, slender bodies of a light 

 color, a dart-shaped tail, large eyes, and ten tentacles, 

 two of which are much longer than the others. 



With these, we close our descriptions of the mol- 

 lusks, and turn to the remaining pages, which will 

 help us in our study of what has gone before. 



