342 



REVISION OF THE MONAXONID SPONGES, 11. 



— presents features which, if allowance be made for probable 

 errors of omission in the original description, afford very good 

 reason for believing it to be a genuine example of the species. 

 For not only do its megascleres mostly conform to the descrip- 



¥\g.5.— Thrinaeophora{t)dathriformis. a, Principal oxea. a', Strongy- 

 lote spicules (presumably abortive forms of the preceding; exceedingly 

 scarce), a". Extremities of principal oxea. h, Interstitial oxea and 

 styli. 



tion, "oxystrongyla slightly curved in the middle and very 

 slightly tapering towards the ends," but — what is especially 

 significant — they also exhibit, at one or both extremities, "a 

 very narrow and sharp spine." This last-mentioned pecu- 



