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typical growth-form takes the shape of a simple encrusting 

 mass, that may be perfectly flat or raised at intervals into 

 more or less prominent hillocks. These prominences may 

 be yet further produced and so subdivided as to give rise 

 to a branching tree-like structure. These several modifica- 

 tions are well illustrated in the common fresh-water sponge, 

 Spongilla Jiiroiatilis, that may be obtained abundantly 

 from the river Thames, growing upon the sides of the 

 locks and submerged tree-roots, almost everywhere above 

 the reach of the tidal waters. A more or less solid globular 

 form, varying in the direction of having the centre so 

 hollowed as to constitute a thick walled cup, or further 

 flattened out in the shape of a somewhat saucer-like ex- 

 pansion, represent the more common modifications of the 

 familiar toilet sponge, Spongia officinalis. A simple sac- 

 shaped or tubular contour is highly characteristic of the 

 little white calcareous sponges {Grantia) and its allies, 

 complex forms with variously branched free or anastomos- 

 ing tubules, as met with in the genera Ascandra and 

 Leucosolenia, representing the more specialized modifica- 

 tions of this type. Elongate tubular or so-called " fistular " 

 forms are also abundantly met with among both the horny 

 and silicious sponge groups, the genus Lnffaria being an 

 example of the former, and the so-called Venus flower- 

 basket sponge, Enplectella aspergillam, of the silicious 

 series. This last-named type, which is a native of the 

 Japanese seas, demands somewhat more extensive notice, 

 since it undoubtedly represents, from an artistic point of 

 view, one of the most exquisitely beautiful productions of 

 Nature's handiwork, and is on this account of marketable 

 value as a household ornament. The first specimen of this 

 sponge brought over to this country from the Philippine 

 Islands, some thirty years ago, was sold for no less a sum 



