KEVIS10N "jiKITISH SPONGIAD2E." 197 



Baspailia ramosa, Mont., XVI. 



,, rectangula, B., LXXXIV. 



„ ventilabrum,~B., X.YI. (Hanitsch, #,p.212.) 



,, virgultosa, B., XIX. 



Genus Acarnus, Gray. 

 Megascleres of the ectosome diactinal (tylota) ; those 

 of the choanosome monactinal (smooth styli) . Accessory 

 megascleres of the choanosome cladotyles, characteristic 

 of the genus. Microscleres isochela3 and toxa. 

 Acarnus stelliferus, B., XXVII. 



Genus Pytlieas, Topsent (18, p. 110). 

 Megascleres of the ectosome usually spined styli, lying 

 tangentially. Skeleton of the choanosome formed of 

 bundles of smooth diactinals, echinated by spined styli. 

 Isochelae usually present. 



Pytlieas inflatus, B., LXXIX. 



Genus Spanioplon, Topsent (18, p. 116). 

 Chief megascleres of the choanosome smooth mon- 

 actinals, few in number as compared with the megascleres 

 of the ectosome, smooth diactinals. "With accessory 

 small spined spicules (microxea, microstyles, or tylostyles). 

 Microscleres (isochelse and sigmata) rarely present. 

 Spanioplon armaturum, B., XXXIV. 



Genus Glathria, 0. Schmidt. 

 Main skeleton formed of well-developed horny fibres 

 cored with smooth styli, echinated by spined styli. No 

 special dermal skeleton. Microscleres isochelae and (or) 

 toxa, sometimes absent. 

 Glathria beani, LVIII. 



,, clavigera, B., XXXVII, 

 ,, laciniosa, B., LXXV. 

 Genus Glathrissa, Lendenfeld, emend. (11, p. 217). 

 Main skeleton formed of dense bundles of diactinals, 

 with very little spongin, echinated by spined styli. With 



