the ' Challenger ' Monaxonida. 473 



sparsely echinated by spined acuates. Spicules : — (1) en- 

 tirely spilled acuates, slightly curved, gradually sharp-pointed, 

 size "42 by "016 millim. ; (2) as (1), but much smaller, and 

 usually straight, size "16 by '012 millim. (echinating) ; 

 (3) smooth bicapitate cylindricals, with small oval heads, 

 size '3 by '0094 millim. ; (4) tridentate equianchorates, with 

 only slightly curved shaft, length up to "04 millim. ; (5) 

 bihamates, length up to '057 millim. 



Localities. Off Marion Island, 50-75 fath. ; off south-west 

 coast of Patagonia (var, massa). 



Myxilla compressa^ n. sp. 



Massive (?) , flattened. Yellowish grey. Soft and spongy. 

 Pores in groups. Main skeleton reticulate, with triangular 

 meshes one spicule wide. Spicules : — (1) entirely spined, 

 sharp-pointed acuates, size '28 by '0155 millim.; (2) as (1), 

 but smaller, size '12 by '008 millim., echinating the fibre ; 

 (3) smooth cylindricals, somewhat hastately pointed, or with 

 small oval heads, pointed at the ends, size '22 by '0063 

 millim. ; (4) tridentate equianchorates, shaft very strongly 

 curved, length "044 millim.; (5) bihamates, length '02 millim. 

 (very rarely up to "063 millim.). 



Locality. Station 320, off the Rio de la Plata, 600 fath. 



Myxilla iiohiUs, n. sp. 



Massive or lobate, may be incrusting. Greyish yellow. 

 Soft, spongy, rather cavernous. Pores in groups. Spi- 

 cules: — (1) acuates, entirely smooth or very slightly spined 

 at base, slightly curved, gradually sharp-pointed, size '52 by 

 •03 millim. ; (2) much smaller, entirely spined, straight 

 acuates or spinulates, size '18 by '013 millim. (echinating) ; 

 (3) bicapitate cylindricals, heads slightly expanded, very 

 short, abruptly truncated, often slightly spined at the end, . 

 size *33 by •00G3 millim. ; (4) tridentate equianchorates, shaft 

 stout, strongly curved, length up to '044 millim. ; (5) bi- 

 hamates (?). 



Localities. Station 148 A, Southern Ocean, 240-550 fain. 



(var. ?) ; Station 320, off the Rio de la Plata, 600 fath. (type) ; 



Station 311, off south-west coast of Patagonia, 245 fath. (var. 



jjatayonica).] Station 307, south-west coast of Patagonia, 140 



fath. (var. bacillifera). 



Myxilla f rondo say n. sp. 

 A single broad, flattened frond, \ inch thick. Tough, 



