no SPONGES 



as a natural family the Pharetronidae, which Dendy wishes to distribute 

 amongst tlie other Heterocoela. 



Grade A. Homocoela, Pol., s. Ascones, H. 



Gastral layer continuous. 



Family 1. Clathrixidae, Minchin. Form reticulate. Triradiate 

 systems always present, equiangular ; monaxons present or absent. Collar 

 cells with nucleus at base. Larva a parencliymula. Genera — Clathrina, 

 Gray { = Ascetta, H., pars. Ascaltis, H., pars., etc, and Leucascus, D.) ; 

 Figs. 2, 6, 7, 8 ; Ascandra, H., emend. { = Homa)idn(, Ldf., for Ascandm 

 falcata, H.) ; Dendya, Bidder, for Clathrina tripodifcra, Crtr. Family 2, 

 Leccosoleniidae, Minchin. Form erect ; monaxons always present ; 

 triradiates, if present, alate ; collar cells with nucleus apical ; larva an 

 amphiblastula. Genera — Asajssa, H. ; Leucosolenia, Bwk. ( = .(4sca«rfra, H., 

 pars., etc.) ; Figs. 3, 4, 5. 



Grade B. Heterocoela, Pol. 



Gastral layer discontinuous and restricted to chambers. 



Family 3. Svcettidae, D. Chambers elongated, radially arranged 

 round the central gastral cavity, their ends projecting on the dermal 

 surface, not covered by a dermal cortex. Tubar skeleton articulate. 

 Genera — Sijcetta, H., emend. ; Sycon, Risso, emend. (Figs. 9, 10) ; Sy- 

 caniha, Ldf. Family 4. Grantidae, D. With a distinct and continuous 

 dermal cortex covering over the chamber layer, and pierced by inhalant 

 pores. No subdermal sagittal triradiates, nor conspicuous subgastral 

 quadriradiates. The Hagellated chambers vary from elongate and radially 

 arranged to spherical and irregularly scattered ones. The skeleton of the 

 chamber layer varies from irregularly articulated to irregularly scattered. 

 Genera — Grantia, Fleming (Fig. 11); Ute, O.S. ; Amphintt', ILui. ; 

 UteUtty D. ; AiiamixiUa, Pol. ; Sycyssa, H.; Leucaiidra, H. (inch Polejna, Ldf. ; 

 Vosmaeria, Ldf. ; and Teichonella, Crtr., Figs. 12 and 71) ; Eilhardui, 

 Pol. (Fig. 1 3) ; LeucyssajH. ; Lamoiitia, Kirk. Family 5. Hetkhopidae, 

 D. A dermal cortex as in the last. Subdermal sagittal triradiates 

 present. Flagellated chambers as in the last. An articulated tubar 

 skeleton may or may not be present. Genera — Granteiiga, Ldf. ; Hetewjua, 

 Crtr. ; Vosmnerop.^ts, D. Family 6. Amphoriscidae, D. A dermal 

 cortex as in the last. Conspicuous subdermal ([uadrimdiates, with 

 inwardly directed apical rays, are present Flagelhited chambers as in 

 last. Genera — Heteropegma, Pol.; Amphorisciu^, H. ; Syculmis, H. ; 

 Leucilla, H. (including Perichnrax, Pol.) ; Sphenophorina, Breitf. Family 

 7. fPHARETRoxiDAE, Z. Skeleton with fibres formed by interlocking 

 of spicules. Sub-Family 1. Dialytixae, Kff. With all si>icules 

 separate. Genera — LeUipw, Crtr. ; * IHaphctin, Hinde [Ool] : 

 *Eiiplocalia, Steinm. [Tr.] ; *Eud€a, Lamx. [Tr. Jur.] ; *Colosj)oniji'i, 



t Fossil aud recent. 



