176 ZOOPHYTES. 



of the Sertularia, fig. 3. Its margin is serrated, or divided into obtuse 

 jn-ocesses, which also cover the surface, fig. 4. No regularity prevails in 

 the dimensions ; large and small vesicles are in close approximation ; their 

 colour, apparently derived from the contents, is greenish or yellowish. 

 They are transparent when empty. 



Though I have had many specimens at various seasons of the year, 

 which were preserved with every possible care, the opaque vesicles became 

 empty and transparent, without discharging any visible object. All my 

 endeavours, which were not few, to discover the nature of their contents, 

 have been defeated. 



At different times I have been induced to question whether these in- 

 numerable muricate bodies, thus investing, even totally obscuring, the parts 

 beneath them, are truly vesicles, or whether they are not rather extraneous 

 substances. I conjectured them to be the capsular progeny of some of the 

 Testacea, especially from the almost invariable presence of a minute solen, 

 concomitant on that of the vesicle ; and which may be seen crawling on 

 the same twig, bearing both vesicles and living hydrse, as well as crawling 

 on the sides of vessels with specimens, and on other parts, fig. 5, a, l>. 

 However, nothing has hitherto verified that conjecture ; nor have I heard 

 that the mode of propagation of the Sertularia miiricata has been deter- 

 mined by observers. 



Plate XXXII. Fig. 1. Sertularia muricata. 



2. Hydra enlarged. 



3. Portion with muricate vesicles, enlarged. 



4. Vesicle magnified. 



5. Portion with a hydra, a ,• and a minute solen, i, enlarged. 



§ 8. Sertularia (Plumularia) falcata. — The Sickle Coralline. — 

 Plates XXXIII. XXXIV. — The arrangers of the Systema, finding the 

 multiplication of species inconvenient, have endeavoured to rectify it by 

 the strange expedient of erecting some of the species into genera, and for- 

 tifying that project by a new name, as if nomenclature, instead of physio- 

 logy, were the foundation of permanence. Thus a few have been selected 



