266 PROCEEDINGS OF THE ACADEMY OF [1887. 



Sponge yellowish-green ; creeping upon and around water-plants 

 and roots, matting them together and thus forming loose, irregular 

 masses several inches in diameter, often including shells of Planor- 

 his and other snails. Less frequently it is found encrusting the up- 

 per surface of stones or the gravelly bed of a stream to the depth of 

 two or three lines. Sponge itself of no describable form. 



Gemmuloe spherical, light yellow or brown, rather numerous among 

 the skeleton spiculse and the attached roots ; granular crust charged 

 with birotulate spicules. Foramina sub-elliptically enlarged and 

 prolonged to a length about equal to one fourth the diameter of the 

 gemmule. Just below its rounded termination it gradually flares 

 and divides into two to five ta2)ering, slender, curling or twisted ten- 

 drils, whose length may be as much as a half an inch. These cir- 

 rous appendages or prolongations of the chitinous coat of the gem- 

 mule in this species are generally round, but occasionally, near their 

 origin, are flat for a short distance. (PI. VI, fig. vi.) 



Skeleton spicules slender, subfusiform, gradually pointed, very 

 sparsely microspined. (PI. XII, fig. iv. a. a.) 



Dermal spicules slender, nearly straight acerates, entirely spined ; 

 spines longer near the middle of the spicules. (Ibid, d.d.d.) 



Birotulate spicules with cylindrical shafts, abundantly spined ; 

 spines as long as the rays of the rotules ; acutely conical. Rays of 

 supposable rotules numerous, spreading outward like a burr or brush ; 

 often with a spinous prolongation in the line of the shaft. (Ibid. b. 

 b. e.c. e.e.) 



Mean. Skeleton spicules 0-0098 by 0-00025 inches. Length of 

 dermal spicules 0-0028 inches. Birotulate spicules 0-0018 by O'OOOl 

 inches. Diameter of disk O'OOOG inches. 



Hah. As described. 



Loc. Lansdowne Run, Centennial Grounds, Philadelphia ; Le- 

 high River, Bethlehem, Pennsylvania; Rahway River, New Jer- 

 sey, etc. 



The visitor to the American Centennial Exposition of 1876, wheth- 

 er foreigner or "to the manner born," if but for a minute he with- 

 drew his eyes from that wonderful display of human art and rested 

 them upon the natural beauties of the landscape in the midst of 

 which it was placed, can hardly even now fail to remember the "Lake" 

 with its evei- flowing geyser fountain, lying north of "Machinery 

 Hall." Escaping by a passage under the "Belmont Road," the over- 



