ON MERLTA NORMANI. 693 



sponge, and further, there need be no hesitation in phiciug 

 it in the family Haplosclerid^. At one time I had regarded 

 the clavidiscs as modified chelae, on account of the existence 

 of two minute knobs on one of the " teeth " of a developing 

 form, but it soon became evident that the affinities of these 

 spicules were with the sigmata. If the free ends of the 

 diancistra of Hamacantha were united it would become a 

 clavidisc. Merlia, with its tylote megascleres, its rhaphides, 

 trichodragmata, sigmata and toxa, is nearly related to the 

 Desmacellin^, a sub-family into which Lundbeck (11) places 

 the three genera, Biemma, Desmacella, and Hamacantha. 

 The scattered vertical tufts visible through the surface of 

 Merlia in whole decalcified specimens somewhat resemble 

 similar tafts at the oscular and poral surfaces of Eiemma 

 rosea Fristedt (H). Occasional horizontal bundles of 

 spicules lying on the tabuh\3 in Merlia might be compai*ed 

 with the deeper-lyiug spicular network in B. rosea. 



The presence, however, of clavidiscs and of a peculiar type 

 of canal system in Merlia necessitate the founding of a new 

 sub-family, viz., Merlina?, which should be placed next to 

 ])esmacellina3. 



It would beau interesting experiment to cultivate Merlia 

 iu lime-free sea-water. If the sponge survived such depri- 

 vation the calcocytes would probably at first continue to heap 

 up or build a soft skeleton similar in shape to the hard one, 

 but later, being unburdened with lime, would resume their 

 original functions as ordinary amoebocytes. 



(7) On Some Resemblaxces between the CALCAiiEOus Skele- 

 ton OF Meelia and Certain Paleozoic Organisms, 



The calcareous skeleton of Merlia undoubtedly presents 

 striking superficial resemblances to certain Pala30zoic fossils, 

 such as certain Monticuliporas, and to Rhaphidopora 

 stromatoporoides from the Devonian of Gerolstein (PI. 38, 

 figs. 7, 8, 9). In each case there is a surface polygonal 



