28 ZOOPHYTES. 



ciliated gemmule. But we discover no analogy between them and the 

 Actinia perpetuating its race by a ciliated gemmule also. The Flustra 

 hispida spreads in adhesion, the Alcyonium gelatinosum rises erect. They 

 have no common resemblance. But both originate from ciliated gem- 

 mules, which becoming stationary are converted to cells ; and additional 

 cells form in union with the first. The Botryllus, a compound ascidia, 

 discharges the spinula, a minute active animalculum, like a tadpole, which 

 becoming stationary, adheres to a foreign substance, and metamorphoses 

 to an Ascidia, from which others originate, as with the Alcyonium. 



Which of all the preceding features ought to be selected as the 



foundation of the character? It would perplex even those deeply versed 



in natural history to be satisfied with a choice. 



Thus our arrangements must always remain of uncertain permanence, 



at least until the subject be infinitely better understood ; and our business 



ought meantime to be assuming those predominant appearances which 



shall preclude any difficulty of recognition. 



§ 1. Flustra hispida. — Plate IX. — The introduction of this species 

 here, is more from the difficulty of finding a proper place for its reception, 

 than from conviction of having assigned it the true position in the natural 

 scale of zoophytes. Indeed, were it not for assuming a certain provisional 

 latitude, much inconvenience might result from prematurely endeavouring 

 to bring certain subjects within the sphere of a precise definition. Thus, 

 let us now take but a general view of an ascidian hydra, combined with a 

 peculiar gelatinous substance. 



The properties of individual products determine their place. 

 The Fucks senatus, or sea-ware, so common on our rocky shores, is 

 frecmently invested by dark brownish gelatinous-like consistent patches on 

 one or both sides of the leaf, also occasionally encircling the stem. These 

 are sometimes in such profusion that the leaf is weighed down, or if reft 

 from its site it feals heavy in the hand. 



The numerous inequalities of the surface, both to the naked eye and 

 when viewed by a magnifier, bear some resemblance to artificial manu- 



