238 LIVERPOOL BIOLOGICAL SOCIETY. 



Fig. 2. Vertical section through the massive form of Cl'wua 

 celata, Grant (X 3). 



Plate XII. 

 Fig. 1. CUona celata, Grant, not quite one-half natural size. 



Plate XIII. 



Fig. 1. A portion of the choanosome of Seirlola compada, 

 Hanitsch, showing chamber-system, strand of 

 "problematic cells" (in longitudinal section), 

 and cystenchymatous tissue (X 250). 



Fig. 2. Transverse section through a strand of " proble- 

 matic cells" of Selriola comjmcta, with cys- 

 tenchymatous tissue around it (X 250). 



Fig. 3. Section through the choanosome of Selriola com- 

 pacta, showing the branching of the strands of 

 " problematic cells " (X 50). 



Fig. 4. Portion of fibrous layer of Selriola compacta, situated 

 between ectosome and choanosome (X 250). 



Plate XIV. 



Fig. 1. Vertical section through the upper portion of the 

 ectosome of Stelletta colling si, Bowerbank. The 

 encroaching Sycamlra cillata (in the upper left 

 corner of the plate), shown diagrammatically, 

 (X 200). 



Fig. 2. Spined portion of a prionorrhabd (X 800). 



Fig. 3. a, chiaster (X 800) ; h, c, and d, forms of oxyaster 

 (X 400). 



Fig. 4. a, protrigena; l>, dichotriEena (X 60). 



Plate XV. 

 Fig. 1. Portion of transverse section through Leucaltls 



Impressa, n. sp. (X 80). 

 Fig. 2. Two specimens of Leucaltls Inipressa, natural size. 

 Fig. 3. a, h, c, and d, triacts and tetracts of the body- wall 



(X 150) ; /, gastral tetract (X 150). 



