Mr. H. J. Carter on the Nomenclature of the Tetliyadfe. 103 



thyadae in situ, it should be remembered that there are no 

 anchor-heads at all in T. casula, and that where (in most of 

 the species) they are present thej are as plentiful in the upper 

 portion and free surface of the body of the Tethya as in any- 

 other part ; while in the fixed or sessile form of T. arabica 

 the base of this hemispherical sponge is agglutinated to the 

 rock by a layer of horny sarcode ; and therefore it is pro- 

 bable that the agglutination of the spicules in the conical ex- 

 pansion of T. casida to the sand serves to fix it there as much 

 as the spicules. 



The minute bihamate and contort C- and S-shaped spicules, 

 with which the sarcode of the head in T. casula is densely 

 charged, finds its equal in every respect in T. cranium (Bower- 

 bank, Brit. Spong. vol. ii. p. 85) and inT. arabica {I. c). It 

 is also present in like manner in T. atropurpurea (Annals, 

 1870, vol. vi. p. 176, pi. 13), but larger and spinous towards 

 the extremities. It, together with the anchor-headed spicule, 

 might have existed in T. dactyloidea [ih. 1869, vol. iii. p. 15); 

 but, unfortunately, I had given the specimen to Dr. Bower- 

 bank before I saw the desirableness of examining it more 

 minutely. 



So the presence of this minute spicule would appear to be 

 characteristic of the Tethyadge generally ; for it is mentioned 

 by Schmidt in Tetilla polyura (Atlant. Spong. Faun. 1870, 

 p. 66), although it is unnoticed in his passing observations on 

 Tetilla euplocamus (Spong. Algier. 1868, p. 40, and Atlant. 

 Spong. Faun. p. 66), which came from Desterro, on the coast 

 of Brazil, and, having no separate description allotted to it, 

 may have had no special examination. 



Why Schmidt should have changed the name of Tethya to 

 Tetilla (Atlant. Spong. Faun. p. 60, Tetilla cranium) and have 

 retained it for the sponges of which Tethya lyncurium is the 

 type, I am at a loss to conceive. 



Nomenclature of the Tethyadce. 



In 1750 Donati* introduced the word " Tetie " for that 

 sponge to which, among others, Lamarck, in 1802, gave the 

 name of Tethya lyncurium\. 



Risso, in 1826, first used the name of Tethya craniumX^ 

 which was apjjlied to the British species by Fleming in 1828§. 

 In 1833 Nardo introduced the term of Donatia aurantium for 



* Nat. Mar. dell' Adriat. 64, tav. 9. fig. a, b, &c, (ap. Johnston), 



t Ann. du Mus. t. i. p. 71. no. 5 (ap. Blainville, Man. Actiuol.). 



i L'Europ. M^rid. vol. v. p. 364 (ap, Johnston). 



§ Hist. Brit. An. p. 519 (ibidem). 



