272 Mr. R. Kiikpatiick on the Mona,voneUida 



Sphcerotylus antarcticus, sp. n. 



Sponge dome-shaped or spheroidal, attaclied or free. 

 Surface beset with a dense short pile of cortical microtyles ; 

 with several usually elongated papillse with or without a 

 large terminal orifice. Dermal pores distributed over the 

 cortex, each pore opening into a single tubular canal in the 

 cortex ; the mouth or pore of the pore-canal is guarded with 

 a ring of radiating cortical tyles. Flagellated chambers 

 diplodal. 



Skeleton formed mainly of radiating fibres composed o£ 

 styles, with diverging brushes of spherostyles near the sur- 

 face. Cortex with a surface-layer of densely packed tufts of 

 small vertical tyles, and a subcortical layer of tangential 

 styles and tyles. 



Sjnciiles. — Spherostyles 8 mm. in length by 30 [x, m 

 diameter in the middle, and 14 yu. in the region below the 

 distal knob ; distal knob 28 /m in diameter, hemispherical, 

 with granular surface and with a few square teeth or serra- 

 tions on the edge. 



Styles straight, fusiform, blunt-pointed, 2*8 mm. in length, 

 41 fjb in diameter in the middle, 23 fx in diameter at the 

 rounded end. 



Cortical tyles curved, 146 fj, long, head 3"25 /x in diameter ; 

 neck slender, 2" 75 /x thick, with broad oar-blade-like shaft, 

 but circular in section, 7 fi thick. 



Styles of lower cortical tangential layer, also in choano- 

 some, 900 X 20 fi. Tyles of the same layer nearly straight, 

 270 /i long, with head 7 jm in diameter and relatively thick 

 neck 6'S fi in diameter. 



Slender, curved tyles, 460 x 10 /i, scattered in choanosome. 



Young specimens are oval, with one long closed papilla; 

 the bundles of divergent exotyles are more or less separate 

 and distinct, and the distal knobs retained and not broken 

 ofF. 



Locality. Winter Quarters, 10-30 fath. 



SiGMAXiNYSSA, gen. nov. 



Cup-shaped Axinellidae with longitudinal skeletal fibres 

 joined by transverse ones on the inner aspect, and with tufts 

 given oft' at right angles to these on the outer aspect. Mega- 

 scleres, oxeas ; microscleres, sigmata and toxa. 



Sigmaxinyssa pJialellioides, sp. n. 

 Sponge sessile, cornucopia- or cup-shaped. Inner surface 



