M. K. A. Zittel on Fossil Litldstidxe. 241 



Ileterosimia, Zitt. (Cretaceous). Vase-like, stalked, with branched roots. 

 Wall on both surfaces with ostia and radial canals. Skeleton con- 

 sisting partly of large branched megamorine, and partly of smaller 

 knobby rhizomorine elements. 



Family 3. Anomocladina. 



Skeletal elements consisting of four or more smootli arms 

 meeting- in a tliickened centre ; arms forked at the end 

 (PL VIII. fig. 5). Bacillar spicules arc also present in great 

 abundance. 



Melmella, Zitt. (Jura). Globular or pyriform, with wide central cavity, 

 into Avhich arched canals open. Oblique radial canals running up- 

 wards and outwards from the centre are also present. Base with 

 siliceous epidermis. 



Cylindroph/ma, Zitt. (Jiura). Cylindrical, with wide central cavity. 

 Radial canals horizontal. 



LecaneUa, Zitt. (Jura). Basin-.^haped, thin-walled. Canal-system ab- 

 sent. 



Mastosia, Zitt. (Jura). Nodular, with warty elevations ; siu'face with 

 fine pores. 



Family 4. Tetracladina. 



Skeletal elements quadriradiate, the four arms branched or 

 thickened at the ends, with four axial canals meeting at angles 

 of 120° (PL VIII. fig. 1). Surface-spicules generally present 

 in abundance (forked anchors, lobate or entire siliceous disks, 

 and bacillar spicules). 



a. Sponge-body hemispherical to trochiform, not adherent. 

 Base coated with a wrinkled siliceous membrane. Skeletal 

 elements indistinctly quadriradiate, the smooth arms strongly 

 branched at the ends. Stomachal cavity simple, with ostia 

 of curved canals ; besides these, radial canals obliquely directed 

 outwards. 

 Aulocopiimi, Oswald (Silurian). 



h. Sponge-body cylindrical, pyriform, globular, rarely 

 basin-shaped, simple or branched. Skeletal elements with 

 four equal, smooth, rarely somewhat knobby arms, ramified 

 at the ends. Surface with forked anchors and uniaxial 

 spicules. 



Phymatella, Zitt. (Cretaceous). Cylindrical, with nodular excrescences. 



Central cavity wide. Radial canals horizontal. 

 Aulaxinia, Zitt. (Cretaceous). Elongate, pyrifonn, massive. Surface 



with longitudinal furrows, in which radial canals open. Root with 



distorted elongated skeletal elements (PI. VIII. fig. 2). 

 Callopegma, Zitt. (Cretaceous). Basin-sliaped, with wide central cavity. 



Surface A\ith forked anchors. 

 Trachysycon, Zitt. (Cretaceous). Fig-shaped, with tubular stomachal 



cavitv. Surface with conical warts. Radial canals horizontal. 



