46 Mr. H. J. Carter on 



animals in eitlier organic or inorganic calcareous material ; 

 communicating with the exterior through tlie stoloniferous 

 canals. 



Differing from all other sponges in their habitat is that 

 family for which I have proposed the above name ; but as 

 thej equally differ from each other in their spiculation it 

 also becomes necessary to group them accordingly. Hence, at 

 the end of my illustrated description of Alectona Millari 

 (Journ. Roy. Micros. Soc. 1879, vol. ii. p. 493, pi. xvii.), 

 they have been divided into three genera with the suggestion 

 of a fourth for the genus " /S'amws," which, typically con- 

 sidered, would respectively lead to the formation of the 

 following groups, viz. " Clionina," '•' Thoosaina," " Alecto- 

 nina," and '' Samusina." To the paper in the journal men- 

 tioned, as well as the ' Annals ' of 1880 (vol. vi. p. 56 &c., 

 pi. V.) and those of 1879 (vol. iii. p. 350 &c. pi. xxix. 

 figs. 1-7), I must refer the reader for all the information 

 that I have hitherto been able to contribute on this subject. 



Fam. 3. Pachytragida. 



" Char. More or less corticate with cancellous more or less 

 radiated structure internally ; well differentiated." 



On this family I published a paper in the * Annals ' of 

 1883 (vol. ii. p. 344 &c.), therefore need not repeat anymore 

 of it here except that I found it necessary to intercalate 

 between Stellettina and Tethyina a fourth group under the 

 name of " Theneanina," whose history, characters, and classi- 

 fication will be found in the same paper (pp. 354 to 362 in- 

 clusively). 



Also to this family I would still add another group under 

 the name of " Stellettinopsina," immediately after Stellettina, 

 for species of the genus Stellettinopsisj which promise to be so 

 numerous as to claim this distinction. They are principally 

 characterized by possessing only one form of skeletal spicule, 

 and this a large, smooth acerate, like the body-spicule of 

 Stelletta, together with one or two forms of the stellate spicule, 

 as noticed in the illustrated description of my type-species 

 SteUettinopsis simplex, from which the rest of the characters of 

 this group may be extracted (' Annals,' 1879, vol. iii. p. 349, 

 pi. xxviii. figs. 16-18). 



New species of all the groups in this family have also been 

 described here and there in the ' Annals,' to which respec- 

 tively I must again refer the reader for further information on 

 ihis subject. 



