278 PROCEEDINGS OF THE ACADEMY OF [1887. 



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

 three hooked rays ; c,c,c,c, spined bii'otiilates of the shorter 



Fig. II. Heteromeyenia argyrosperma, var. tenuis. From Harvey's 

 Lake, Pennsylvania :-a,a,a, slender skeleton spicules ; b,b,b 

 long birotulates ; c,c, birotulates of the shorter class ; all 

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



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

 a,a,a, microspined skeleton spicules ; b,b, 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 Flainfield, 

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

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

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

 lected by A. D. Balen. 



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

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

 mule birotulates, hooked and spined ; c,c,c,g,c, short birot- 

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

 face microspined or granulated ; e, amorphous spicule. 



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

 Scotia :-a,6,e, 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; b,b,b, 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, 

 "insequibirotulates ;" 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,e,d,d, birot- 



