50 ZOOPHYTES. 



CHAPTER II. 



TuBULARiA (Sertularia) Ramea. — Plates VI. VII. VIII. IX. X. 



^ § 1. The Tubularia proper is distinguished by two prominent charac- 

 teristics ;^r5/, In the hydra having a double row of tentacula ; second, In an 

 ovarium of pendent clusters, near the stomach, being interposed between 

 them. I have found none in Scotland, unless the two preceding species, 

 with similar organs thus disposed. As neither of these features, palpi or 

 clusters, is presented by the subject of this paragraph, it ought certainly to 

 be incorporated with the SertularicB, or perhaps assigned to an interme- 

 diate place. 



Some recent authorities, indeed, propose to denominate it Euden- 

 drium, which is rather more adapted for a specific than a generic distinc- 

 tion, especially from being inappropriate to nine-tenths of the specimens 

 occurring, and in applying with equal force to many other zoophjiies. 



The hydra seems precisely of the same structure and habits as that 

 of the Sertularia. It propagates, with exception of some peculiarities, 

 precisely after an analogous fashion, through the medium of a prolific pod 

 or vesicle ; the progeny issuing from this most narrowly resembles the 

 planula, which we shall see is discharged by the other, insomuch that for 

 facility of indication they may pass by the same name. 



Here, however, no cavity terminates the extremities of the product, 

 adapted for reception of the numerous hydrse; there are neither the cylinders, 

 sheaths, nor bells of most Sertularia; ; and they can only contract, instead of 

 enjoying the privilege of retreating. But this important safeguard is not 

 only incomplete in various species of the Sertularian tribes, but, when na- 

 turalists have even founded the systematic name and arrangement on its 



