STUDIES ON TBE COMPARATIVE ANATOMY OF SPONGES. 257 



Figs. 52 — 54. — Grantiopsis cylindrica. Calcoblasts from the dermal 

 cortex. In Fig. 52 the calcoblast is lying upon a ray of a large triradiate 

 spicule. In Fig. 53 the spicule is partially dissolved by the acid alcohol, and 

 the spicule-sheath is visible. Drawn under Zeiss F, ocular 2. 



Fig. 55. — Grantiopsis cylindrica. Four small mesoderm-cells from 

 the dermal cortex. Drawn under Zeiss F, ocular 3. 



Fig. 56. — Grantiopsis cylindrica. Three subdermal gland-cells, each 

 connected by a long, slender process with the granular dermal surface. Drawn 

 under Zeiss F, ocular 2. 



Fig. 57. — Grantiopsis cylindrica. Small portion of the dermal surface. 

 Drawn under Zeiss F, ocular 2. 



Fig. 58. — Micro-organisms from the dermal surface of Grantiopsis 

 cylindrica. Drawn under Leitz ^, oil immersion. 



Fig. 59. — Sycon Ramsayi. Contracted epithelium from an inhalant 

 canal. Drawn under Zeiss F, ocular 2. 



Fig. 60. — Sycon Ramsayi. Contracted epithelium from an exhalant 

 canal. Drawn under Zeiss F, ocular 2. 



Fig. 61. — Sycon Ramsayi. Sections of two epithelial cells from an ex- 

 halant canal. Drawn under Zeiss F, ocular 2. 



Fig. 62. — Grantessa erinaceus. Contracted epithelium of an endo- 

 gastric septum, formed by outgrowth of the gastral cortex into the gastral 

 cavity. Drawn under Zeiss F, ocular 2. 



Fig. 63. — Vosmaeropsis Wilsoni. Epithelium from the upper surface 

 of an oscular diaphragm. From an osmic acid specimen mounted in glycerine. 

 Drawn under Zeiss F, ocular 2. 



Fig. 64. — Vosmaeropsis Wilsoni. Contracted epithelium from an ex» 

 halant canal. Drawn under Zeiss F, ocular 2. 



