:274 



ZOOLOGY 



Our commonest Northern sea-anemone is Metridium mar- 

 ginatum (Fig. 2ti3), wliicli occurs on rocky shores south to New 

 Jersey, but reaches its centre of development along the coast 

 of Maine. It varies greatlj^ in color, some individuals being 



est. 7 



^yies t 



Fig. 264. — Sea-am ninu \\'*1 ^ ill partly cait away, (.tentacles. Muscu- 

 lar system; /.///, loiiv^itud i li niusi Ic ; /'.//^ parietal muscles, or those of 

 the body-wall; /" ^pliintri or circular closing, muscles; t.m, trans- 

 verse muscles. Food s^ sicni nd)i mouth; gid, gullet; Sf7p/), siphono- 

 glyph ; vies. 1, 2, .j, mesenteries of first, second, and third order of size : 

 Iji, lappets ; osi. I, 2, openings in mesenteries : tncs.f, mesenterial filaments. 



white, others salmon-colored or oli\'e. The flat u]iper sin-face 

 bears the slit-like opening to the internal sac. Either one or 

 both angles of this slit have thickened edges, and correspond- 

 ing to this difference is a difference in the internal structure. 

 Inside, the central cavity is separated into compartments by 

 radial partitions (Fig. 264). 



