24 A MONOGRAPH OF THE 



this sponge at greater length in a paper published in the 

 'MicroscopicalJournal/ vol.vii, ' Trans. Micr.Soc.,' p. 79, pi. v. 



About the year 1841 or 1842 I received from my Mend 

 the late Mrs. Griffiths, of Torquay, six specimens of small 

 Grantias, which were designated by her " Grantia pulveru- 

 lenta, Spongia Ananas of Montagu." The whole of these 

 specimens agree perfectly with the description of Spongia 

 pulverulenta as given by Dr. Grant, and with Montagu's 

 description of Spongia Ananas, and the pulverulent cha- 

 racter was apparent on all of them ; but on examining 

 them with a power of 130 linear, by the aid of a Lieber- 

 kiihn, I found the pulverulent character arose from their 

 being well-worn specimens, having nearly all the pencils of 

 spicula so prominent in uninjured individuals of all ages 

 and sizes of 67. ciliata broken off close to the summits of 

 the interstitial cells, excepting only in parts near the 

 basal attachment, where they had been protected from 

 attrition, and the ciliary defensive spicula of the month of 

 the cloaca had suffered in a similar manner. I cut up and 

 examined minutely the most characteristic of these speci- 

 mens, but I could not find the slightest structural differ- 

 ence between it and specimens of well-developed Grantia 

 ciliata, and among the numerous specimens I possess of 

 the last-named sponge I found several that from partial 

 injury presented on one side the pulverulent character, 

 while on the other they were unmistakably G. ciliata. 

 I am therefore inclined to believe that Grantia pulverulenta 

 of Drs. Grant, Fleming, and Johnston is but a stunted 

 and worn form of G. ciliata, and is, therefore, not entitled 

 to specific distinction. 



This species runs into a great variety of forms. I 

 have specimens which have assumed the shape of depressed 

 spheres, considerably wider than they are long; others are 

 ovate, and some are seven or eight times their diameter in 

 length ; but in none of these extreme varieties of form 

 have I been able to detect any difference in their structural 

 characters. In some cases the defensive spicula of the 

 inhalent system are rather stouter than in others, but this 

 is probably only an effect of locality. 



