IN SPONGILLA FLUVIATILIS. 61 



It must have been the vicious course of custom — 



" That monster custom, who all sense doth eat 

 Of habits devil," 



That could conduct one of our ablest naturalists to such a decision. 

 The Spongilla of the Exe is identical in character with that of 

 Teddington ; that of Molesey and Surbiton also conform to the 

 same, but are more completely developed ; it is therefore impossible 

 to allow it as a species. It is indeed a very elastic argument that 

 allies it to Sp. Meyeni on the strength of the very slightly developed 

 spination of the spicule, and Mr. Carter does not admit the larger size 

 of the latter as having any specific value, in which opinion I cordially 

 agree. But it is as easy to take a reverse view, and say that S. 

 Meyeni is allied to Sp. jluviatilis, and only a variety from it, and a 

 far more natural conclusion. In fact, it is clear that this Spongilla 

 may be divided into two natural divisions : one having the spicule 

 smooth, the other spinous. Calling the first by its simple title, and 

 the latter variety, in all its developments, with the addition of 

 " spinosa" or " spinifera" and the demands of science would 

 surely be better met. And, as regards the other variations, which 

 I have noticed in both, the letters A, B, C, &c, would serve every 

 purpose. Even in doing this one must not forget that the Tedding- 

 ton sponge gives us evidence of the spination being but a develop- 

 ment from the smooth spicule, so that the idea of a new species, 

 instead of a variety, is out of the question on that evidence alone. 

 The main point in the classification I would propose, is to retain as a 

 general term Sp. ftuviatilis, for we may call that a known quantity 

 whilst those of Meyeni and Parfitti are unknown. Before we can 

 understand them we must go back to the details of our typical forms 

 familiar in books on microscopy, if not from actual examples in our 

 cabinets. The specific terms fluviatilis and lacustris might easily 

 be improved upon, but the names are widely established. Sp. 

 birotalis for the one, and Sp. ramosa for the other — the latter being 

 indeed its old name would be more expressive of their characteristics, 

 and would help us to class the numerous variations, British and 

 foreign, better together. But I am indifferent on that point, so 

 that we can avoid making unnecessary species. Against this we 

 ought to make a stand. Natural history is no longer a study con- 

 fined to a few of scientific leisure : it is now the healthful mental 

 recreation of a large number of the community, embracing those 



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