178 Dzvellers of the Sea and Shore 



zooid cups themselves, compared with which they are 

 greatly inferior. Their purpose is not definitely known, 

 but on occasion they can function as weapons either of 

 capture or of defense. It is supposed, however, by 

 many naturalists, that the nematophores are merely 

 degenerate zooids. Reproduction is of the same type 

 as that of the sertularians; there is no medusa stage. 

 In the genus Anteunidar'ia, however, exists the unusual 

 instance of both male and female zooids in a single 

 colony. 



In a well-shaded spot at the edge of the tide pool, 

 where the overhanging mud bank exposes the mussel- 

 laden roots of the thatch, I often find a hydroid which 

 is incomparably more like a flowering plant than any 

 other species of my acquaintance. Not only does this 

 apply to the polyps, but the colony as a whole has every 

 appearance of a floral bouquet. It grows on the shells 

 of the mussels, yet not infrequently it attaches itself to 

 the dead stems and roots that are imbedded in the side 

 of the bank. Quite dense are its clusters, and fully two 

 inches high; and its amber-tinted stems are terminated 

 by the prettiest of pink hydranths. It is one of the 

 tubularians {Thamnocnidia spectabilis) ^ and so like a 

 certain real plant is it, with its delicate stalks and starry 

 zooids, that it is known everywhere as the passion 

 flower of the sea. 



I think it hardly necessary to point out here that the 

 flowerlike zooids, as is the case with other hydroids, are 

 the nutritive parts, and that their stinging properties, 

 besides assisting in the capture of small organisms, are 

 of considerable help in the animal's defense. But, let 

 me say, this pretty polyp, powerful as it is in its way, 



