SIUCIOUS AND HORNY SPONGES WILSON. 353 



Probably in younger stages of this species the parenchyma of the 

 body extends down over the axial skeleton of the stem. But this in 

 the actual specimen is, as said, quite bare, the parenchyma of the 

 body gradually thinning away, from above downwards, to a sharp 

 edge which encircles its upper end. 



Holotype.—Xo. 21294, U.S.N.M. 



The remaining families of the suborder, denned and in some 

 measure discussed below, are not represented among the forms 

 studied. 



Family CLIONIDAE. 



Clionidae Topsent, 1887. 

 Clioniadae Gray, Vosmaeb, 18S7. 



Hadromerina that bore into and excavate molluscan shells and 

 other calcareous bodies. 



The genera are Cliona Grant, 1826, Dotona Carter, 1880, Thoosa 

 Hancock, 1819, Alectona Carter, 1879, Dyscliona Kirkpatrick, 1900 

 (see Topsent, 1907, p. xx), Clionopsis Thiele, 1905 (see Topsent, 

 1908), Poterion Schlegel, 1858 (see Vosmaer, 1908; George and Wil- 

 son, 1919), Cliothosa Topsent, 1905 (see Topsent 1920, p. 89), 

 Heterocliona Verrill, 1907. 



Family STYLOCORDYLIDAE. 



Stylocordylidae Topsent, 1898. 



Pedunculate forms. Skeleton radiate in the body, longitudinal in 

 the stalk. Megascleres diactinal. Microscleres microrhabds or 

 spherasters, or absent. 



The genera are Stylocordyla W. Thomson, 1873, Cometella O. 

 Schmidt, 1870, Oxycordyla Topsent, 1904. (For Halicometes Top- 

 sent see Donatiidae; also see Topsent, 1920c?, p. 33.) 



Family CHONDROSIDAE. 



Chondrosidae F. E. Schulze, 1877. 



Witli a fibrous cortex. Flagellated chambers small and with spe- 

 cial canaliculi (dipodal type). Megascleres have been lost. Micro- 

 scleres in some forms have been lost. 



The genera are Chondrilla Schmidt, 1862 (with euasters, which 

 may be of more than one kind), Chondrosia Nardo, 1833 (with no 

 spicules). Thymosin Topsent, 1895, with horny fibers, is here classed 

 among the Keratosa (see Psammaplysilla kelleri). Topsent, 1918, 

 p. 603, would add to the family Chondrillastra, new genus. 



Topsent places the family in his Carnosa.. In Delage and 

 Herouard's text and in Minchin's text essentially the same classifi- 

 cation is adopted. 



