'27 S PROCEEDINGS OF THE ACADEMY OF [1887. 



b,b, gemmule birotulates of the longer class, with one to 

 three hooked rays ; c,c,c,c, spined birotulates of the shorter 

 class. 



Fig. II. Heteromeyenia argyrospe7-ma, var. tenuis. From Harvey's 

 Lake, Pennsylvania -.-ajUja, slender skeleton spicules ; b,b,b 

 /0/15' birotulates; c,c, birotulates of the shorter class; all 

 more slender than in the typical species ; d, imperfect do. 



Fig. III. Heteromeyeniq, repens. From Lehigh Gap, Pennsylvania:- 

 a,a,a, niicrospined skeleton spicules ; 6,6, gemmule biro- 

 tulates of the longer class, with recurved, hooked rays ; 

 c,c,c, gemmule birotulates of the shorter class ; d,d,d, ro- 

 tules of do., e,e, dermal spicules; /. amorphous spicule. 



Fig. IV. Heteromeyenia ryderi, var. baleni. From near Plainfield, 

 New Jersey .-a,a,a,a, slender, microspined, skeleton spic- 

 ules; 6,6,6, long, hooked, gemmule birotulates; c,c,c, short 

 do; with flat rotules ; d,d,d, surface of last named. Col- 

 lected by A. D. Baloii. 



Fig. V. Heteromeyenia ryderi, type. From Indian Run, Philadel- 

 phia, Pennsylvania :-a, skeleton spicule ; 6,6,6, long gem- 

 nmle birotulates, hooked and spined ; c,e,c,c,c, short birot- 

 ulates ; d,d,d, surface of rotules, margins lacinulate, sur- 

 face microsi:)ined or granulated ; e, amorphous spicule. 



Fig. VI. Heteromeyenia ryderi, var. pietovensis. From Pictou, Nova 

 Scotia .-a,b,c, densely spinous skeleton spicules, various 

 terminations; d,d,d, long gemmule birotulates; e,e,e,e, 

 short do. 



Plate XII. 



Fig. I. Tubella pennsylvanica. Lehigh Gap, Pennsylvania .-a,a, 

 a,a, spined skeleton spicules ; 6,6,6, gemmule "insequibi- 

 rotulates," or trumpet-shaped spicules ; c, group of ro- 

 tules seen from above, showing the relative sizes of the ro- 

 tules; d, surface of single large rotule. 



Fig. II. Tubella pennsylvanica, var. intermedia. From Indian 

 Run, Philadelphia :-a,a,a, stouter skeleton spicules ; b,c,c, 

 "inajquibirotulates ;" d,e,e, end view of do. showing com- 

 parative size of rotules in this variety. 



Fig. III. Tubella pennsylvanica, var. fanshawei. From Bristol Pond, 

 Pennsylvania .-a,a,b,b, skeleton spicules ; c,c,d,d, birot- 



