138 ZOOPHYTES. 



lection of detached memoirs, it is with less anxiety about their position in 

 systematic order than in the accurate detail of facts. 



Unless in the stationary place of the head or hydra, while subsisting, 

 the double row of tentacular organs, and the pendent ovarian clusters in- 

 terposed between them, few positive distinctions will be found between 

 the general nature of the Tubularia and the Sertularia. A fistulous stem, 

 together with reproduction of the hydra, are not excluded from the latter. 

 But the metamorphosis accompanying the propagation of the Sertularia is 

 an important feature. Nevertheless, were the Tubularia ramea allowed 

 to remain in the position that naturalists now assign it, the correspondence 

 would prove still more intimate in a stem of aggregate tubuli and ovarian 

 vesicles, bearing within them the elements of new generations. 



The extremities of the preceding Tubularise are simply cylindrical ; 

 but, excepting in the last, the Tubularia ramosa, without a tubular cavity 

 wherein the hydra can be withdrawn. The hydra which has rose within 

 the stem to develope from its extremity, remains permanently there. But 

 the extremities of the Sertularia are cellular, and a multitude of cells 

 are implanted on the stem, boughs, and branches, whither the hydra can 

 retreat for shelter, — all of various configuration. Some are little more 

 than a simple orifice : some resemble a tooth, a cup, a flask, or a bell, with 

 a smooth or a serrated lip. Some are armed with a longer or a shorter 

 spine : or the margin of others is guarded by several extraordinary pro- 

 cesses, extending in straight lines or in curvatures of inordinate length. 

 The cells, with their tenants, stand on one or both sides, or around the in- 

 organic parts : they are single, at distant intervals, in pairs, or in clusters, 

 either crowded together or far apart : And they are seated on stalks, or 

 branches, or twigs, jointed, whorled, or frilled. Remarkable profusion, 

 along with the greatest variety, are exhibited throughout the principal and 

 subordinate parts of the difierent genera and species constituting these 

 products in perfection, which nothing but a copious series of accurate de- 

 lineations from luxuriant specimens could illustrate. 



Sertularise are beheld in every stage, advancing from meagreness to 

 the highest luxuriance. That specimen which has an hundred or a thou- 

 sand different hydrse, has an hundred or a thousand different receptacles to 



