Knowledge of the Spongida. 365 



4. Tethyina. 



Lastly, the group Tethyina, whose type is Tethya cranium, 

 Lam. (Johnston, Hist. Brit. Spong. 1842, p. 83, pi. i. fig. 1), 

 is closely allied to all the foregoing both in general structure 

 and in spiculation, although generally the species do not present 

 the " zone-spicule," as will appear hereafter, while the flesh- 

 spicule in all instances yet known, with the exception of one 

 in which it has not been seen, is a minute bihamate (fibula). 

 The term u Tethya" originally derived from TijOv?, mythol., 

 hence rrjdos, an oyster, ttjOvu, Arist., and Ttthea, Pliny, was 

 used by Donati, and thus finally became Tethea and Tethya, 

 Lamarck (Ann. s. Vertebr. 1816, vol. ii. pp. 384, 385), who 

 adopted the generic name of "Tethya" originally used in 1750 

 by Donati for Tethya sj)hcerica( = Tethya lyncurium, Lam.), for 

 a sponge which O. F. Midler had described under the name of 

 Alcyonium cranium , but (ap. Johnston) had not figured (Zool. 

 Danicae Prod. 255, Zool. Dan. tab. lxxv., 1777-1806). 



After this Nardo, perhaps seeing that Lamarck had placed 

 two totally different sponges in the same genus, viz. Tethya 

 (op. et loc. rit.) f substituted the generic term "Donatia" for 

 Donati's " Tethya ;" and thus Tethya cranium, Lam., re- 

 mained the same (' Isis,' 1833). Schmidt, however, reversed 

 the thing, and, returning to Donati's original generic name, viz. 

 " Tethya," invented that of " Tetilla " for Lamarck's 

 "Tethya" cranium in 1870 (Spongf. Atlant. Geb. p. 66), but 

 very rightly separated the two by placing "Tethya" in his 

 Suberitidime and "Tetilla " in his Anchorinidae. Still, why 

 Schmidt should have interfered with the distinction which 

 Nardo had made and Dr. Gray in his proposed classification 

 had accepted, that is, by using the name "Tetilla " for "Te- 



^ meric name, which hejirxt instituted for a 

 sponge sent to lun^hy Fritz Muller from Desterro, in South 

 America, in 1868 (Spong. Kuste v. Algip*, p. 40), I am igno- 

 rant, seeing that the term "Tethya" which Schmidt had re- 

 served for " 1 7 ethya ly natrium" is here said to be in direct 

 relation with the sponge from Desterro which he called "Te- 

 tilla euplocamus" {" an eine directe Verwandschaft "). Had he 

 stopped here and only called the sponge from Desterro 

 "Tetilla" (although, as will be seen hereafter, it is merely a 

 rooted form of tethya cranium that is widely spread under 

 similar conditions in or probably throughout the tropics), one 

 could have only said that " the distinction generically was not 

 called for ; " but when this generic name is carried on in 1870 

 {I.e.) to Lamarck's Tethya cranium so typically established in 

 name and illustration by Johnston in 1842 (Hist. Brit. Spong. 



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