STUDIES ON THE COMPARATIVE ANATOMY OF SPONGES. 255 



PLATE 13. 



Fig. 18. — Grantessa intusarticulata. Portion of a transverse (hori- 

 zontal) section. Drawn under Zeiss A, ocular 2. 



Fig. 19. — ^Vosmaeropsis macera. Portion of a transverse (horizontal) 

 section. Drawn under Zeiss A, ocular 2. 



Fig. 20. — Heteropegma nodus-gordii. Portion of a transverse sec- 

 tion. Drawn under Zeiss A, ocular 2. 



Fig. 21.— Leucilla uter. Portion of a vertical section. Drawn under 

 Zeiss A, ocular 2. 



Fig. 22. — Leucilla australiensis. Portion of a longitudinal (vertical) 

 section. Drawn under Zeiss A, ocular 2. 



PLATE 14. 



Fig. 23. — Vosmaeropsis Wilsoni. Portion of the cortical inhalant 

 canal system, as seen in a transverse section of a specimen killed with osmic 

 acid. The space occupied by the dermal cortex, between the inhalant canals, 

 is left blank, and the pore-bearing dermal surface is shown in perspective. 

 Drawn under Zeiss C, ocular 2. 



Fig. 24. — Ute syconoides. Portion of a tangential section cutting 

 across the radial chambers, showing a chamber in the contracted condition, 

 surrounded by four ordinary chambers and four inhalant canals, portions of 

 which only are drawn. Drawn under Zeiss E, ocular 2. 



Fig. 25. — Leucandra sp. One of the rounded flagellated chambers cut 

 in half. One row of collared cells, with collars united by Sollas's membrane, 

 is seen round the margin, while the observer looks down upon the exhalant 

 opening of the chamber and two prosopyles. Drawn under Zeiss F, ocular 2. 



Fig. 26. — Leucandra sp. Exhalant aperture of another chamber from 

 the same specimen as Fig. 25, surrounded by the membranous chamber 

 diaphragm, in which the nuclei and granules of muscle-cells are seen. Drawn 

 under Zeiss F, ocular 2. 



Fig. 27. — Grantessa intusarticulata. Portion of a section through 

 the gastral cortex and proximal end of a radial chamber. On the right a 

 portion of the chamber diaphragm, marking the junction of the radial chamber 

 with the exhalant canal, is seen in section. On the left a portion of the inner 

 end of an inhalant canal is seen. Drawn under Zeiss F, ocular 2. 



Fig. 28. — Grantessa intusarticulata. Portion of a section through 

 the gastral cortex, showing two of the endodermal pavement cells in section 

 and a stellate cell embedded in the gelatinous ground substance of the meso- 

 derm. Drawn under Zeiss F, ocular 2. 



Fig. 29. — Grantessa intusarticulata. Three contracted ectodermal 

 VOL. 35, PART 2. NEW SEE. T 



