240 PROCEEDINGS OF THE ACADEMY OF [1887. 



Dermal spicules apparently wanting. 



Gemmule birotiilates of the larger class very robust ; shafts long, 

 irregularly cylindrical, often bent, occasionally spinous ; spines long, 

 pointed, perpendicular or recurved. Rays of the rotulse one to four, 

 assuming the form of strong, claw-like hooks, recurved and incurved. 

 (PL XI, fig. i, b.b.) 



Shorter birotulates much smaller, abundantly spined ; spines 

 long, conical. Rotules flatter, irregularly hooked. (PI. XI, fig. i, 

 c.c.c.) 



Meas. Skeleton spicules 0-0109 by 0-0004 inches. Long birot- 

 ulates 0-00543 by 0-0003 inches. Diameter of disks or hooks 0-0012 

 inches. Length of short birotulates 0-0028 inches. Diameter of 

 disk 0-0007 inches. 



Hah. On submerged sticks, stones, etc. 



Log. Lehigh Gap and Holicong, Pennsylvania ; New England 

 States, New Jersey, Nova Scotia, etc. 



No other sponge as yet found in American waters, can compare 

 with this, in the robustness and positive characters of its birotulate 

 spicules. It was first found at Lehigh Gap and has since been gath- 

 ered and received from a few other places. 



Notwithstanding its strong points, the sponge itself has been 

 known to occur only as a delicate incrustation ; or its whilom 

 presence has been recognized by the discovery of the gemmules ihat 

 had been left after nearly all its skeleton spicules had been washed 

 away. 



Heteromeyenia argyrosperma, var. tenuis, Potts. (PI. XI, fig. ii.) 



This variety of H. argyrosperma differs from the typical species 

 chiefly in the extreme slenderness of all its parts. 



Meas. Skeleton spicules 0*0087 by 0*0002 inches. Long birot- 

 ulates 0-00438 by 0-00015 inches. Diameter of rotules or hooks 

 0-0006 inches. Length of short birotulate 0-00297 inches. Diam- 

 eter of its rotules 0-0005 inches. 



Log. Harvey's Lake near Wilkes-Barre, Pennsylvania, and 

 Lake Hopatcong, New Jersey.^ 



1 It will be noticed that the slender forms of well known sponges which have, 

 in this work, been uniformily designated as varieties, have been generally collected 

 in waters at high altitudes, 6". lacustris, v. montana at 2500 feet, (PL VIII, fig. vi); 

 S,fragilis, v. ntinuta, 600 ft.; v. minutissima (PI- VIII, fig. ii.) and v. iri-egtdaris 

 1200 feet; //. argyrosperma, v tenuis, 12(10 ft , (PI. XI, fig. ii); &x\ATueblla penn- 

 sylvanicn, v. tnininia, at 1800 feet above sea level. On the other hand H. ryderu 



