108 ZOOPHYTES. 



ception of the numberless ova, visibly imbedded below, seem preparatory 

 to their liberation, by dissolution of the product wherein they have ori- 

 ginated. 



This Alcyonella occurred in sufficient profusion during several years 

 in a small pond, one scarcely ten or twelve yards in diameter, between 

 Queen Street and Heriot Row, in the centre of the city of Edinburgh. 

 Here also is the abode of the Vorticetta rotatoria, which might be seen 

 affixed to the hydra, with its ciliated apparatus to each side in apparent 

 revolution. 



I have never observed the Alcyonella otherwise than as a single stra- 

 tum, investing the surface of leaves, or surrounding their pedicles. Dur- 

 ing summer, however, I once found in the same place as above, a detach- 

 ed rudely cylindrical dark spongy mass, exceeding eighteen lines in length, 

 and half as thick, of cellular structure. The numberless cells were all 

 empty, with a few white hydra? interspersed among them. But no .more 

 continuing to appear, I rent the mass asunder a short time afterwards, for 

 examination of the interior. On pouring water over it a multitude of ova 

 escaped, exactly resembling the ova of the superficial grey patches forming 

 the Alcyonella from the same pond. They produced many hydra? before 

 the last day of June. 



Probably the white hydra? within were from some of the ova of pre- 

 vious seasons there. As nothing could sanction the supposition of this 

 uncommon mass being generated in a single season, if belonging to years 

 preceding it may have been different from the subject of the present para- 

 graph. Its general appearance was not unlike the polyparium of the 

 Alcyonella fluviatilis of Raspail. Possibly the A Icyonetta staxjnorum grows 

 in much greater luxuriance than I have ever seen it. If the preceding mass 

 was of this species, it must have been the accumulation of many years. 



Much has to be understood regarding this subject, and especially 

 whether important modifications may not be concomitant on the peculiarity 

 of its site, and the period during whicli it has subsisted. 



There is so little correspondence between the Alcyonium and the 

 Alcyonella, that a preferable name might have been bestowed on the 

 latter, than what is so obviously derived from the former. But when 



