PLATE 19. 
Purisiphonia ClarJcei, Bowerbank. 
ig. 1. A fragment of the wall of the sponge, showing the outer surface and the 
apertures of the canals. Natural size. Drawn from the type specimen, 
described by Dr. Bowerbank, and now in the British Museum of Natural 
History, South Kensington. 
l'ig. 2. The same specimen viewed laterally, showing the thickness of the wall and 
the course of some of the canals. 
li b . 3. A portion of the outer surface^ enlarged 12 diameters, showing the disposition 
or the fascicles of linear spicules and the oscular apertures. 
4. A fragment of the spicular-mesh of the interior of the sponge-wall, showing 
its irregular character. Enlarged 60 diameters. 
Eig^. o and 6. Fragments of the fascicles of the linear spicules. Enlarged 60 diameters. 
Pigs. 7, 8, and 9. Entire and fragmentary hexactinellid spicules from the interspaces 
of the spicular-mesh. Enlarged 150 diameters. 
Tig. 10. A group of minute hexactinellid spicules, confusedly intermingled and 
cemented together. They occur in the canals of the sponge-wall. 
Enlarged 60 diameters. 
Pig. 11. Portions of rosette flesh-spicules. Enlarged 250 diameters. Drawn from the 
slide in the possession of Mr. H. J. Carter, E.R.S. [All B.M.] 
G. J. H. 
