1887.] NATURAL SCIENCES OF PHILADELPHIA. 217 



skeleton spicules of Tuhella pemisylvanica ; which species has fre- 

 quently been found in contact or in close proximity with the other. 



A singular effect upon the spicules of this sponge, produced 

 either by a retardation of their growth, or a hastened disintegration, 

 was noticed (Proc. Acad. Nat. Sci. 1884, p. 184) in the case of frag- 

 ments that had grown within certain old water pipe^, and were, at 

 the time of examination, strongly marked by iron rust. A central 

 canal nere occupied fully one half the width of the skeleton spicules 

 and was open at both extremities ; and the birotulates had lost 

 their "entire" margins and appeared delicately rayed. 



It may be mentioned in this connection, that this species, more 

 frequently than any other, has been found encrusting iron water 

 pipes ; their exteriors, when they have long lain exposed to the 

 Avater ; and the interiors of those of large size, to a distance of some 

 hundreds of feet from the reservoirs, where they had grown of 

 course, in entire darkness. I have not yet succeeded in finding 

 either the sponge m situ, or its detached spicules, among the concre- 

 tions that occasionally entirely close the water-way of some of the 

 smaller pipes, near the centre of our city. 



(3) Meyenia gregaria, (S, gregaria) Bk. Proc. Zool. Soe. etc., 1863 p. 452. 



"Skeleton spicula cylindrical, stout and rather short. Ovaria 

 fiirnished with an envelope , spicula of the envelope few and scat- 

 tered, cylindrical, short and stout, entirely spined. Ovaria, surface 

 even, furnished abundantly with very short birotulate spicula ; ro- 

 tulse flat, margins entire, outer surface umbonate ; umbo very short, 

 slightly convex. Shaft of spiculum cylindrical, short and stout. 

 Color in the dried state dark, lurid green." Bowerbank. 



Hab. "River Amazons, on branches of trees, periodically pendant 

 in the water; near Villa Nova." 



I have been able to identify several small groups of gemmules of 

 this species on the stem of a twig supporting a mass of Parmula 

 brownii, var. from Beni River, East Bolivia. As in this situation I 

 have been so fortunate as to find and determine positively the spicular 

 skeletonof the sponge itself which neither Dr. Bowerbank nor H. J. 

 Carter had done, the following is offered as a complete description. 

 It will solve some doubts of both the former authors. 



Sponge minute, encrusting, thin ; surface even ; orifices very nu- 

 merous, large. Skeleton spicules not fasciculated, consequently no 

 long lines of fibre, the spicules attached and crossing one another in 

 every direction. 



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