258 PKOCEEDINGS OF THE ACADEMY OF [1887. 



with the chitinous coat, where it is overlain by an extremely thin 

 development of the microcellular crust, from which the lacinuliform 

 processes above mentioned are projected." Carter. 

 Loc. British Guiana. 



Parmula brownii, var. tuberculata, n. var. 



Sponge as seen in a dried state, dark brown, massive, spherical ; 

 enveloping the small twig upon which it had grown. Mass ex- 

 tremely rigid, spinous at the superfices ; reticulations many times 

 larger than those of any known North American sponge. (The sar- 

 code and dermis have now almost entirely disappeared.) 



Gemmules numerous ; granular crust rather thin, surrounded by 

 a dense capsule of spicules, the interstices of which it penetrates by 

 numerous fibre-like extensions, which, when seen in small white 

 rounded prominences outside the capsule, give it a peculiar mottled 

 appearance. The gemmules are firmly attached by their capsular 

 spicules to the radiating and connecting lines of skeleton spicules 

 near their outer extremities, and form a continuous zone just within 

 the mass. 



Skeleton spicules smooth, robust, nearly cylindrical, but slightly 

 thicker at the middle ; terminations abruptly pointed. Those of the 

 capsule are similar, but about one half the length of the former and 

 more curved. Many of them are covered with large and beautifully 

 rounded tubercles which are the marked features of this variety. 



Dermal spicules very minute, slender, spined acerates; spines at 

 the middle long, perpendicular, rounded. 



Gemmule spicules parmuliform or shield shaped ; consisting of a 

 subcircidar proximal rotule with entire margin, then rapidly tapering 

 into a central boss or spine whose length may be equal to one third 

 or one half the diameter of the rotule. These are embedded under 

 the crust resting upon the chitinous coat. 



Hah. Upon trunks and branches of submerged trees. 

 Loc. Beni River, East Bolivia, S. A. Collected by Dr. H. H. 

 Rusby. 



The specimen of this variety of P. hrownii, received from Dr. 

 Rusby is about five inches in diameter, very rigid to the touch, but 

 with meshes relatively very large, so that it was possible to see 

 through the mass nearly at the centre. Its attachment to the 

 twig around which it grew, is, at present, but slight, the twig hav- 

 ing shrunken away from the primaiy supporting membrane. The 

 radiating lines of skeleton spicules, slender at first, have gradually 



