EXPLANATION OP THE PLATES. G77 



Fig. i. Stelhtta clavosa, acerato, anchoring quadriradiate, and zone 

 spicules, x 08. i' , head of zono- spicule, as seen from 

 ahove, x 68 ; i", stellate flcsh-spicules, x 370. From typo 

 specimen from Prince of Wales Chanm 1. 



j. S. purpurea, acerate, anchoring quadriradiate, and zone- 

 spicules, x 08. /, stellato ilesh-spicules, x 370. From 

 type specimen from Torres Straits. 



Tc. S. purpurea, var. retroflesca, the zone-spicule, x 68. From 

 specimen from Torres Straits. 



I. Tethyopsis dissimilis, diagrammatic vertical section* across 

 upper end of larger f specimen from Port Darwin, x about 

 2. V . The same* of smaller specimen from Port Darwin, 

 X about 3 [the dark parts represent canals, the dotted 

 portions those occupied by the skeleton and tissues in the 

 Sponge itself]. I". Portion of dermis J from between two 

 longitudinal skeletal lines, from larger specimen from 

 Port Darwin, as seen from inside, x about 25. V". Part 

 of septum between two large canals, from same specimen, 

 X about 25. I"". Skeleton triradiate spicules, one normal, 

 the other with abnormally elongated third ray, x 34. 

 I'"". Acerate spicule from small Port-Darwin specimen, 

 and I""", from Torres-Straits specimen, x 34. I" 1 "". Flesh- 

 spicules from larger specimen from Port Darwin, x 850. 



m. Leucaltis bathyhia, var. australiensis, tri- and quadri- 

 radiate spicules of outer surface ; m', triradiate from 

 centre of wall ; m", quadriradiates of subjacent parts. All 

 X 68. From type specimen from Port Jackson. 



n. Stellettinopsis carteri, the skeleton-spicule, X 68. ri , the 

 larger, and n", the smaller stellates, x 370. From type 

 specimen from Torres Straits. 



* Canals. — 1, antei-ior ; 2, posterior; 3 and 4, lateral; 5 and 6, antero- 

 lateral ; 7 and 8, postero-lateral ; 9 (in I), axial. 



t Note. — Since writing the account of the canals (given at p. 478 of Part I. 

 of the Report), I have disrovered that the apparently single pair of lateral spaces 

 in the larger specimen is in reality double. 



\ Showing that the long arm of the skeleton-spicule commonly extends over 

 two interfascicular spaces, and is not confined to one as stated in the description 

 at p. 477. 



