APPENDIX. 241 



kinds chiefly confined to the surface, where they are 

 arranged vertically with their heads toward the dermal 

 layers and their shafts internally; the stellates, although 

 most numerous and packed together crust-like in the 

 dermal layer, are also scattered throughout the body- 

 substance; while the sheaf- like bundles of minute 

 acerate spicules are entirely confined to the latter. 



Habitat. — Budleigh-Salterton (Carter). 



I am inclined to think that Stelletta lactea of 

 Carter may be synonymous with Tethya Gollingsii, 

 Bowerbank ; but Carter figures the two forms of 

 stellates as of equal total diameter, whereas in T. Gol- 

 lingsii the long rayed form is some three times the 

 diameter of the short rayed, and has far fewer rays ; 

 in T. Gollingsii, moreover, the bifurcating trifid 

 spiciJa are few and are evidently a mere variety of the 

 recurving trifids. 



4. RiSNiERA Paefitti, Bow. 



Beniera Pa/rfitti, Bowerbank. In Parfitt Marine and Freshwater 

 Sponges of Devonshire. Trans. Devon. Ass. Advanc. Liter. 

 Science and Art, 1868, p. 10. 



" Massive, sessile ; surface smooth, somewhat undu- 

 lated ; oscula simple and sparsely distributed, slightly 

 raised above the surface ; pores inconspicuous to the 

 unassisted eye; dermal membrane abundantly spicu- 

 lous ; spicula very irregularly disposed, imbedded in 

 the membrane ; spicula acerate, stout, with a few more 

 slender ones intermixed, of two sizes ; skeleton spicula 

 very numerous, acerate, stout, suddenly and acutely 

 pointed, tooo^^ of ^^ i^ch long and Tob~o^^^i of aii iiich 



VOL. IV. 16 



