ADDITIONS AND CORRECTIONS. 195 



Tethea LyncuriUiM, p. 85. 

 Under the description of this species, (p. 86,) I have express- 

 ed a belief that it and the Cydonimn Mulleri of Fleming were 

 identical, but having since received from the Rev. Dr Fleming 

 a slice of his Cydonium, I am now aware that my conjecture 

 was entirely erroneous. The Cydoniima in question is a species 

 of the genus Geodia of Lamarck, provided the definition of 

 that genus is modified so as to meet the views of Milne-Edwards. 

 See p. 57. I have therefore to introduce to my readers a native 

 species of this very interesting genus, which, in a system of clas- 

 sification, should take its place nigh to Tethea. 



GEODIA,* Lamarck. 



Geodia, Lam. Anim. s. Vert. 2de edit. ii. 593 Audoutn et Milne- 

 Edwards, Hist. Nat. du Lift, de la France, i. p. 77. Blainv. 

 Man. 534. Schweig. Hajidb. 422. 

 Character. Sponge tuberous, solid, permeated with ir- 

 regular sinuous canals ; the interior composed of siliceous spi- 

 cula collected into fascicles, and laid amid an organic sarcoid 

 matter ; the surface covered with a solid crust composed of si- 

 liceous globules closely agglutinated together. Marine. 



\. G. Zetlandica, the crystals of the surface globular, 

 with a minutely reticulated surface. 



Plate III. Fig. 3, 4. 



Alcyonium Cydonium ! Jameson in Wern. Mem. i. 563. Stew. 



Elem. ii. 432. 



Cydonium Mullen ! Flem. Brit. Anim. 516. Grant in Edin. New 



Pliil. Journ. i. 195. Johnston's Brit. Zooph. 191. 



Hab. Deep water. " Island of Fulah and Unst," Jameson. 



The interior of this remarkable sponge is fulvous and of a 



loose cottony or asbestine texture when dry. The spicula are 



numerous and collected into bundles trending from the base or 



centre to the skin, which some of them penetrate, but the points 



scarcely project beyond the surface. A sheath of organic mat- 



* From yiuSiic, earthy, eartblike. 



