On a new Species of HexactinelUd Sponge. 275 



I take this opportunity to state, in reference to my report in 

 the 'Annals' for November 1872, that the white variety of 

 Tectura tesMcUnalis, MiilL, of wliich I obtained many fine spe- 

 cimens in Iceland, is likewise met with on the North-British 

 coasts ; and, possessing seemingly as strong claims to varietal 

 distinction as many other named varieties do, I trust my pro- 

 posed designation may not be deemed inappropriate. 



1 may also call attention to a slight printing-error which 

 occurred on page 373, viz. Punctura instead of Puncturella. 



2 Ampton Place, W.C. T. A. VerkruZEN. 



XXX. — Description of Labaria hemi^phajrica. Gray, a new 

 Species of HexactinelUd Sponge, loith Observations on it 

 and the Sarcohexactinellid Sponges generally. By H. J. 

 Carter, F.R.S. &c. 



At the request of Dr. Gray I have examined Labaria hemi- 

 spherical the sponge sent by Dr. A. B. Meyer to the British 

 Museum from Singapore ('Annals,' vol. xi. p. 235, March 

 1873) ; and the following is its general and microscopic de- 

 scription. 



Labaria hemisphmrica, Gray. 

 Sponge sarcospiculous, hexactinellid, now dry and colour- 

 less. Cup-like, massive, hemispherical, convexo-concave. 

 Sides thick, margin obtuse, round, slightly contracted, con- 

 cavity shallow. Surface of interior even, uniform ; that of the 

 convexity or exterior the same, but interrupted here and there 

 by the presence of linear spicules, which project microscopically 

 in a line round the outer border of the margin, tlien disappear, 

 leaving a plain convex surface, but reappear towards the 

 lower third, where, gradually becoming longer and congregated 

 into small tufts, they finally end in a large stem-like bundle, 

 which on issuing from the base of the sponge is half an inch 

 wide, and spreads out into a tassel two inches long. Vents ? 

 (see Obs^. General structure of the body chiefly composed of 

 smooth nail-like spicules, Avith four-armed heads, of different 

 sizes, varying from such as can be easily seen with the un- 

 assisted eye down to microscopic minuteness, all knit together 

 by the nail-like shaft being directed inwards, and the crucial 

 arms expanded and interweaving with each other horizontally ; 

 thus, with the largest spicules on the surface, and their arms 

 bent a little inwards, the whole are bound down, as well over 

 the concavity as over the convexity, into a firm basketwork 

 with even exterior. Internal structure, as seen by transmitted 

 light through the surface, cavernous or largely cancellous, with 



18* 



