EDITOEIAL NOTE. 
This Volume contains a comprehensive Report on the Tetractinellid Sponges 
collected during the Expedition, by Professor W. J. Sollas, LL.D., of the 
University of Dublin. It forms Part LXIII. of the Zoological Series of 
Reports, and extends to 622 pages of letterpress, illustrated by 44 chromo- 
lithographic plates, a map, and a large number of woodcuts. Professor Sollas 
has added a notice of species not met with in the Challenger collection ; this 
Report forms therefore a complete monograph of the group. 
The Manuscript was received by me in Instalments between the 31st 
August 1886 and the 24th February 1888. 
This Report concludes the account of the Sponges collected by the 
Expedition. The other Reports dealing with this large group have been 
published as follows : — 
Part XXIV. (Volume VIII.), Report on the Calcarea, by X. Polejaeff, 
published in 1883. 
Part XXXI. (Volume XI.), Report on the Keratosa, by X. Polejaeff, 
published in 1884. 
Part LIX. (Volume XX.), Report on the Monaxonida, by S. 0. Ridley 
and A. Dendy, published in 1887. 
Part LIII. (Volume XXI.), Report on the Hexactinellida, by F. E. 
Schulze, published in 1887. 
Challenger Office, 32 Queen Street, 
Edinburgh, \2th May 1888. 
John Murray. 
