60 PAPILLINA. — BAPHTRU8. 



millim. ; the more slender branches which supply the ciliated chambers are 

 very narrow and rendered invisible by contraction in spirit-specimens. The 

 exhalants join to form oscular tubes 1'5 millim. wide, which terminate in 

 the scattered, equally wide, circular oscula. 



Skeleton. — The supporting skeleton is composed of spicule-bundles which 

 ramify in a dendritic manner and have a thickness of O'5-l millim. ; micro- 

 sclera are very abundant. — (1) Megasclera. Styli and tylostyli, measuring 

 0'4x0"012 millim., straight, abruptly pointed at one end; the bulb where 

 developed spherical, situated terminally, on an avei-age 0*02 millim. in diameter ; 

 the tylostyli are more numerous than the styli. These spicules form the 

 bundles above mentioned, and are also very abundant, scattered irregularly 

 throughout the ground-substance ; a great many are situated in the 

 surface, and there lie either tangentially or more or less oblique to the 

 surface; some protrude 0*2 millim. beyond it. — (2) Microsdera. Spineo 

 strongyla, 0*05 x 0*008 millim. ; the spines are not numerous, about fifteen tc 

 each spicule, sharp-pointed, and as long as the spicule is thick ; these micro- 

 sdera are mostly straight, although irregularly curved ones are not unfrequent ; 

 they are very abundant throughout the sponge. 



Geogeaphical Distribution. — East coast of Australia: Port Jackson, 

 N. S. AV. {Ramsay). 



Genus RAPHYRUS. 



Spirastrellidse with a regular honeycomb-like structure in the 

 interior and a regular network with hexagonal meshes, correspon- 

 ding to this, on the surface. This network consists of lines raised 

 over the general surface of the sponge. The bulk of the micro- 

 sdera are short and stout, spined strongyla. 



In 1862 Oscar Schmidt * described two sponges 2i& PapUUna suberea and 

 P. nigricans, from the Mediterranean ; in 1866 Bowerbauk t described a 

 sponge as Raphyrus Griffitlisii, which has also been figured +. Oscar 

 iSchmidt afterwards § combined this Raphyrus of Bowerbank with his own 

 Papillimi suberea, an arrangement which has been followed by Norman ||. 

 The genera Raphyrus, Bowerbank, and Papillina, O. Schmidt, would according 



* O. Schmidt, Die Spongien des Adriatischen Meeres, 1862, p. GO. 

 t J. S. Bowerbank, Monograph of the British Sponges (Eay Society), vol. ii. p. 354. 

 \ J. S. Bowerbank, Monograph of the British Sponges (Ray Society), vol. iii. pi. Ixiv. 

 § O. Schmidt, Grundziige einer Spongienfauna des Atlantischen Gebietes, 1870, p. 77. 

 II A. M. Norman, Monograph of the British Sponges, by the late J. S. Bowerbank (Ray 

 Society), vol. iv. supplementary, p. 182, 



