Sponges from South Australia. 279 



unable to conceive, unless he considered that both were only 

 variations of the same sponge, which I think very likely, 

 especially as the form of ^^ polychotoma " very often runs into 

 that of " oculata ; " and Johnston himself, as before noticed, 

 has placed them together, that is one after the other, in his 

 * British Sponges.' But then neither "ocw/ato" nor " j)olt/- 

 chotoma^'' possesses a flesh-spicule, which Chaliuapalmata does, 

 and Johnston did not know this ; so something else must have 

 influenced him in using this designation, probably the desig- 

 nation '■'■ jpalmata^'' which Ellis used for the sponge that 

 Johnston considered to be his '"'' Halicliondria joalmata ; " 

 still, as before stated, unless it could be proved that Ellis's 

 sponge contained the peculiarly formed anchorate to which I 

 have alluded, it is quite as likely, as just stated, that his sponge 

 was a mere variety in form of Ghalina polycliotoma. 



So much for confusion in nomenclature when names are 

 based on mere resemblances ; but it should be remembered 

 that all this took place before the achromatic microscope had 

 been invented, after which distinctions on minute differences 

 which then came into view were rendered comparatively 

 easy. We know, however, now that Johnston's Halichondria 

 palmata differs in possessing the peculiarly-formed anchorate, 

 to which I have above alluded, from all the other Chalinida, 

 and that the species is identical with the " Mermaid's Glove." 



The chief distinguishing characters of the order Ehaphido- 

 NEMA, in addition to the diagnosis above mentioned, are their 

 easily yielding to pressure and corresponding resiliency, from 

 the keratose element of the fibre predominating, the spicular 

 element more or less scanty, the structure loose, and, as Ellis 

 noticed in 1786 {pp. cit. p. 185), " the gelatinous part of the 

 flesh [the sarcode] is so tender that when it is taken out of the 

 water it soon dries away." In structure the deeper part is 

 generally less dense than the circumference, which is also 

 generally the opposite in the following order, viz. the ECHI- 

 NONEMA ; hence the former are for the most part easily com- 

 pressible, while the latter are generally much less so, and 

 often even absolutely hard. In spiculation there is generally 

 only one form of spicule, and that is the simple or commonest 

 form of acerate, viz. smooth, curved, fusiform, and sharp at 

 both ends ; while in the Echinonema there is generally more 

 than one form, of which one is generally acuate, that is an 

 acerate with one end obtuse. In the Rhaphidonema the ske- 

 letal is seldom accompanied by a flesh-spicule, while in the 

 Echinonema it is seldom without one. The spicule in the 

 Hhaphidonema is generally confined to the fibre, hence its 



