ESSAY ON SI^ONGES. 



69 



that great illuminator in this science, could not 

 define them : amongst these, Alcyonium and 

 Spongia seem to rest nearly where they were left 

 by Ellis. Of the former, if we were to confine 

 the genus to an aggregate of polypes, enclosed 

 within superficial cells, (which appears essential,) 

 then several of the species of Alcyonium would be 

 removed, particularly lyncurium, tydoniuniy bursa, 

 and perhaps some others. In these three, no stel- 

 late pores or cells, nor polypes, haVe ever been 

 observed. 



Bursa is without doubt a Conferva. Lyncurium 

 and cydonium approach very near to Spongia ; but 

 these, with two or three others of similar struc- 

 ' ture, might perhaps be formed into a new genus^ 

 if any advantage to science could be gained by it. 

 However, till we are better acquainted with more 

 of this intricate family, I shall arrange two or 

 three of the same structure (which are perhaps 

 new) in the genus Spoiigia^ as bearing strong cha- 

 iracters of such^ according to the Eliisian defini- 

 tion. 



The animals of this genus, the most inert and 

 least definable by means of the animal itself^ are ex- 

 tremely obscure | consequently it is not suflicient 

 that such anomalous beings be described in half a 

 dozen of words, which is all we have to direct us 

 with respect to many species. In most instances, 

 shape is not to be depended upon ; and, as the 

 greater part of the sponges we obtain, are thrown 

 ashore by the sea after storms, few are found 



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