614 SUMMARY OF CURRENT RESEARCHES RELATING TO 



tical with S. stagnalis Dawson, was obtained. Another lacustrine 

 form, which is not quite S. lacustris, was brought from the lake near 

 Catskill Mountain House. Its status has not been fully determined. 



From the cellar of an old ruin at Lehigh Gap, Pennsylvania, four 

 species were obtained which appeared to be new. These were all 

 thin, creejnng or encrusting sponges, three of them of the birotulate 

 type, briefly described as follows: — S. argyrosperma. — Seed-body or 

 sph^rulse large, silver-white, densely covered with radial spiculse, 

 the shafts of which are long, stout, with numerous long spines, 

 straight or curved ; the rotulae at each end being replaced by 1-4 

 strong recurved hooks. 



S. repens. — Found creeping over the stems and leaves of Pota- 

 mogeton ; sphaerulfe also closely covered with spicula, shorter and 

 more slender than those of the preceding species ; their shafts nearly 

 smooth, the rays of the rotulfe, six, eight, or more, uniformly in- 

 curved like the ribs of an umbrella. 



S. astrosperma. — The sphaerul^e have the appearance of being 

 much smaller than in either of the former species, which is probably 

 due to the fact that the birotulate spicula surrounding the real 

 capsules are very short ; the length of the shaft being less than the 

 diameter of the rays. They are rather sparsely scattered over the 

 surface of the nearly transparent sphere, suggesting the name star- 

 seeded. 



The remaining form is considered a variety of S. fragilis, and 

 called minuta ; sphserul® much smaller than in the type species, the 

 dermal and superincumbent spicula terminated by sharp points, 

 while in the other they are universally truncate or rounded. 



Mr. H. Mills also records * a variety of Spongilla lacustris found 

 in Niagara Eiver. 



History and Classification of Spongilla.f — Mr. H. J. Carter gives 

 a most useful resume of the fresh-water sponges, commencing with the 

 first public notice of them by L. Plukenet in 1696, and including the 

 researches of W. Dybowsky, which we noticed ante, p. 256. The 

 Bibliography includes 32 papers. 



The fresh-water sponges are, according to Mr. Carter, the fifth 

 family (Potamospongida3) of the sixth order (Holoraphidota) of the 

 Spongida, and the classification which he proposes of the group 

 Spongillina is based not on the form of the skeleton-spicule, which is 

 almost always more or less alike in all, but chiefly on the spicules of 

 the seed-like reproductive organs or statoblasts, the possession of 

 which at present constitutes a sharp line of demarcation between the 

 marine and fresh-water sponges. Of the genera into which the Spon- 

 gillina are divided (formerly all treated as belonging to the one 

 genus Spongilla), Spongilla has ten species (three n. sp.), Meyenia 

 eight (one n. sp.), Tuhella four (one n. sp.), Parmula two, and Uruguaya 

 (n. gen. prov.) one. A statoblast is at present unknown in the latter 

 genus. 



* Amer. Journ. Micr., vi. (1881) pp. 30 1. 



t Ann. and Mag. Nat, Hiat., vii. (1881) pp. 77-107, 203 (2 pis.)- 



