. Fresh-water biology. Freshwater biology. Sponge evergreen, encrusting, thin, sending out numerous long, slender waving branches from a relatively thick basal membrane. Gemmules few, in scattered branches. Skeleton spicules smooth, straight or slightly curved, rather abruptly pointed. Dermal spic- ules minute, smooth, straight or curved, slender, gradually pointed. From clear standing water in New Jersey and Virginia. Fig. s6o. Spicules of Spongilla aspinosa. Four types of spicules figxured here; ordinary skeleton spicules abruptly pointed at both ends; skeleton spicule, acute or rounded at o
. Fresh-water biology. Freshwater biology. Sponge evergreen, encrusting, thin, sending out numerous long, slender waving branches from a relatively thick basal membrane. Gemmules few, in scattered branches. Skeleton spicules smooth, straight or slightly curved, rather abruptly pointed. Dermal spic- ules minute, smooth, straight or curved, slender, gradually pointed. From clear standing water in New Jersey and Virginia. Fig. s6o. Spicules of Spongilla aspinosa. Four types of spicules figxured here; ordinary skeleton spicules abruptly pointed at both ends; skeleton spicule, acute or rounded at one end; malformations of skeleton spicules, with processes at or near one end; small smooth dermal spicules; globular or discoidai masses of silica frequently observed in this species. X loo. (After Potts.) 4 (3) Flesh spicules spined Spongilla lacustris (Linnaeus) 1745. Branches cylindrical or tapering, and rigid. Prefers rapidly running water. Very abun- dant. Gemmules either apparently wanting or abundant throughout the sponge, with or without a granular crust. Skeleton spicules smooth. Dermal spicules pointed spined acer- ates. Gemmule spicules whether few or many generally cylin- drical, more or less curved, rather sparsely spined. From Boston, Mass., to McDonald Lake, Alaska, in an infinite number of situa- tions and variety of forms. The variety paupercvla Bowerbank, made an independent species Spongilla pauptrcula by Carter, "is perhaps that one of this group of synonyms about whose identity with 5. lacustris there may be most hesitation. Its character is some- what anomalous, as its locahty and associations are peculiar. Grow- ing originally in the ponds and reservoirs tributary to the Boston Water supply, Bailey wrote in t8s6 that it grew abundantly in the waterpipes by which the city was supplied with water from a small 'lie qSr Skeleton and eem- ^^^^" ^'^^ minute acerates were said to have been smooth which mule spicules of Spon^ would separate it clearly
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectfreshwa, bookyear1918
