OF THE SPONGIAD^E. 269 



FIG. 



in the course of their further development they 

 assume a monilliform appearance, as represented 

 by Fig. 239, and in their adult state are verticil- 

 lately spined, as represented by Fig. 238. 



240. INFLATO-ACERATE, with incissurate terminations. 

 X 660 linear. From Hymerapliia verticillata, 

 Bowerbank. A terminal portion only of this spi- 

 culurn is represented by the figure, the incissurate 

 character being the only novelty in the form. The 

 incissuration varies in degree to a considerable ex- 

 tent in different spicula, in some cases being very 

 slightly produced, in others rather beyond that re- 

 presented by the figure. The rudiments of a third 

 ray are sometimes apparent. This form is an aux- 

 iliary skeleton spiculum. They are found thickly 

 clustered round the primary spicula of the skeleton. 

 They differ essentially from porrecto-ternate spicula 

 in having both ends cleft or radiate, which is never 

 the case in any of the ordinary ternate forms. 



SPICULA, THE POSITIONS OF WHICH ARE UNKNOWN. 

 241. BlRECURVO-QUATERNATE, MEDIALLY SPINED. Sponge 



unknown, X 660 linear. Probably an internal 

 defensive spiculum. 



242. SPINULATO-ENSIFORM, from a parasitical sponge from 



Western Australia. X 130 linear. I obtained 

 this singular form from a parasitical sponge from 

 Western Australia. This curious sponge, in the 

 formation of its skeleton, appears to have appro- 

 priated the spicula of every other kind of sponge 

 that came within its reach. 



243. ACUATE : BASALLY RECTANGULATED. X 150 linear. 



1 obtained this spiculum from the spongeous 

 matter scraped from the base of Oculina rosea, 

 by a dealer in the process of cleaning the coral. 

 It is not a malformation, as there are several 



