2 THE VOYAGE OF H.M.S. CHALLENGER. 



In the simple form and arrangement of the spicules this is the most primitive of all 

 genera of siliceous sponges. It is characteristic of littoral regions in most or all parts 

 of the world, but never seems to occur in deep water. Schmidt was the first to really 

 restrict the genus within reasonable limits/ but Vosmaer ^ has shown that he was in 

 error in overlooking the earlier name Halichondria. 



The original type of the genus is the well known and cosmopolitan species 

 Halichondria panicea. 



Halichondria 2oanicea, Johnston (PL II. figs. 2, 3). 



1842. Halichondria panicea, Johnston, ^ British Sponges, p. 114, pi. x. and pL xi., fig. 5. 



1870. AmorpJiina panicea, Schmidt, Spong. Atlant. Gebiet., p. 77. 



1881. Amorplmia megalorhaphis, Carter, Ann. and Mag. Nat. Hist., ser. 5, vol. vii. p. 368. 



1884. Amor2Jhina megalorrhaphis, Eidley, Zool. Coll. H.M.S. "Alert," Brit. Mus., p. 416. 



1885. Amorphina megalirrhaphis, Eidley, Narr. Chall. Exp., vol. i. pt. ii. p. 571. 



Vosmaer * has already given a good abstract of the history of this old and well- 

 known species, to which we must refer the reader. A good description of the species is 

 to be found in Johnston's British sponges [he. cit.), and stiU further details are given 

 by Bowerbank.^ 



Carter^ has already described a specimen of Halichondria panicea (var.) from 

 Kerguelen, which was obtained by the Transit of Venus expedition. Later {loc. cit. 

 sup.) he describes his Amorphina megalorhajMs, from the Basse Eocks, Ceylon, and 

 in so doing makes the following observations : — " This seems to be a variety of the 

 common British species Halichondria panicea, chiefly difi'erentiated by the size of its 

 largest spicules, which is double that of the English one. The spicules also of the 

 specimens brought home by the Rev. A. E. Eaton from Kerguelen's Island, and others 

 dredged up by H.M.S. "Porcupine" in the Atlantic Ocean, are much larger than those 

 of the common British species ; so that this variation may extend even to our own 

 shores, while the single form, great variety in size, and long attenuation towards the 

 end of the spicule generally characterise the species everywhere." 



We have now to record a series of specimens '' from Kerguelen, which to our mind 

 completely establish the identity of the British Halichondria p)anicea with Mr. Carter's 

 Amorphina megalorhaj)his. 



While agreeing remarkably well in external form these specimens (of which there are 

 seven or eight of fair size, in addition to smaller pieces) exhibit a great range in the 



1 Amorphina, loc. cit. 2 Bronn's Klass. u. Ordnung. d. TMerreichs, Porifera, p. 337. 



^ For probable synonyms of older writers, vide Johnston, loc. cit. 



* Bronn's Klass. u. Ordnung. d. Thierreichs, Porifera, p. 336. 



' Mon. Brit. Spong., vol. ii. p. 229. « Phil. Trans. Roy. Soc, vol. ckviil p. 286. 



' One of these specimens was figured in the preliminary account, Narr. ChaU. Exp., vol. i. pt. ii. p. 571, fig. 188. 



