244 PROCEEDINGS OF THE ACADEMY OF [1887- 



Last autumn I 'collected in Gilder Pond, Berkshire Co. Massa- 

 chusetts, already described, a sj^onge as different in. its general ap- 

 pearance from the typical form of H. ryderi, as can well be imag- 

 ined, but with similar birotulate spicules ; and their very dissimilar- 

 ity in external form led me to think of H. jjidovensis, in which the 

 gemmule spicules are also like those of H. ryderi. It was not at all 

 willingly, but rather in spite of an exceedingly rebellious disinclina- 

 tion, that I came at last to the conclusion that the others had no 

 sufficient claim to specific distinction, as H. ryderi typified and in- 

 cluded them all. 



The strongest member of this species is the variety H. pidovensis, 

 next to be described. (PI. XI, fig. vi.) I have only seen rather 

 minute specimens of it, but believe it to be both massive and com- 

 pact, and nearly smooth in surface and outline. A form found in 

 the Lehigh River at White Haven, comes next, also with strongly 

 sj^inous skeleton spiculse and very robust birotulates. Then comes 

 the typical form from Philadelphia, described above as externally 

 hemispherical, but composed of compacted lobes. In the next 

 v. tvalshii, from Gilder Pond, I imagine the lobes have separated 

 and spread out into the slender, subdividing branches mentioned in 

 the description of that variety. The series probably terminates with 

 the delicate features of v. haleni (PI. XI, fig. iv,) which will most 

 likely be found also branching. 



Heteromeyenia ryderi, v. pictovensis, Potts. Proe. Acad. Nat. Sci. Phila. 

 1885, p, 28. (PI. XI, tig. vi.) 



Sponge light green, even when dry ; massive, encrusting. Text- 

 ure very compact ; spicules non-fascicnlated, persistent. Surface 

 mostly smooth. 



Gemmules as discovered very scarce, spherical; crust thick. 



Skeleton spicules cylindrical, short, robust, rounded or abruptly 

 terminated, entirely spined ; spines conical at the middle of the 

 spicule, elsewhere generally curving forward toward each extremity. 

 Hounded terminations of spicules covered with short spines, though 

 frequently a single large spine or acute termination is seen at one 

 or both ends. (PL XI, fig. vi, a.b.c.) 



Dermal spicules absent or undiscovered. 



Birotulates of the longer class surrounding the gemmules rather 

 numerous, one third of their own length longer than the others; 

 shafts mostly smooth, consjjicuously fusiform, frequently with one 



