130 EUSPONGIA. 



the bath-sponge, one of which, a-rroyyia nvKros, belongs to this species. All 

 the older authors refer to it. Linne established the name Spongia officinalis. 

 O. Schmidt described a number of distinct forms which P. E, Schulze 

 afterwards placed in this species. A. Hyatt attempted to classify all these 

 forms, and also to take into account those described by Duchassaing and 

 Michelotti. Hyatt's work is very cumbersome, and his species, subspecies, 

 and varieties are evidently untenable and quite unrecognizable from his descrip- 

 tions. With the aid of the excellent photographic plates which accompany 

 Hyatt's work I have, however, been enabled to recognize a number of his 

 forms, which are distributed among the varieties. 



Euspongia officinalis, var. moUissima, 0. Schmidt. 



Euspongia officinalis, var. moUissima, F. E. Schulze, " Untersuchungen iiber den 



Ban und die Entwicklung der Spongien. — VII. Mittheilung. Die Eamilie 



der Spongidae," Zeitschrift f iir wissenschaftliclic Zoologie, Bd. xxxii. Seite 



616 (1879). 

 Spongia moUissima, 0. Schmidt, Die Spongien des adriatischen Meeres, Seite 



23 (1862). 

 Spongia officinalis, subspecies mediterranea, var. moUissima, A. Hyatt, " Eevi- 



sion of the North American Poriferte. — Part II.," Memoirs of the Boston 



Society, vol. ii. p. 511 (1877). 

 Spongia officinalis, subspecies mediterranea, var. zimocciformis, A. Hyatt, 



I c. p. 511 (1877). 



GrEOGEAPHiCAL DISTRIBUTION. — Mediterranean (0. Schmidt, F. E. Sclmlze). 



Euspongia officinalis, var. dura, Hyatt. 



Euspongia officinalis, var. dura, E. v. Lendenfeld, " A Monograph of the Aus- 

 tralian Sponges. — Part VI. The Genus Euspongia," Proceedings of the 

 Linnean Society of New South Wales, vol. x. p. 531 (1885). 



Spongia lignea, A. Hyatt, " Revision of the North American Poriferae. — 

 Part II.," Memoirs of the Boston Society, vol. ii. p. 511 (1877). 



Irregular, horizontally extended sponges, which show indications of the 

 formation of conic processes on the upper surface, and attain a maximum diameter 

 of 160 millim. The surface is continuous and pretty smooth, the oscula are 

 scattered and small. The dry skeleton is hard, according to Hyatt (loc. cit.), 

 like cork. 



The skeleton is, according to Hyatt (loc. cit.), very dense, more so than that 

 of any other sponge. This is, however, very much exaggerated. The main 

 fibres are on an average 0-5 millim. apart, closer together than in any other 



