of the National Antarctic Expedition. 231 



mammillae ; surface finely reticulate and finely hispid. 



Colour creamy white in spirit. Consistence soft, the tissues 



bein^ easily torn. The flesh reddish (but soon decolorized), 



and showing the glistening white strands of the skeleton. 

 Oscules in form of wide, thin-wallod, cylindrical chimneys 



with rather jagged upper edges, about 1 cm. in height and 



1-2 cm. in diameter. 



tSheleton. — Ectosomal : a network of triangular meshes 



formed by bundles of oxeas, the strands being about '35 mm. 



thick and the meshes about '5 mm. across. Main skeleton 

 formed of long thick anastomosing fibres, which attenuate 

 gradually from 1*5 ram. in thickness and break up a little 

 below the surface into panicles of much finer fibres, which 

 support the dermal membrane and penetrate the strands and 

 nodes of the dermal reticulum, giving rise to a finely hispid 

 condition of the surface. Parallel groups of oxeas scattered 

 in the choanosome. 



Spicules. — Megascleres : oxeas, 850 X IG 25 {m, slightly 

 curved, rather abruptly pointed at one end and more tapering 

 at the other. These oxeas form tiie fibres and also are 

 gathered into bundles, one spicule in length, of parallel oxeas, 

 scjittered in the choanosome. 



Microscleres : large anisochel^e palmatae, 105 X 50 /a, sepa- 

 rate or in rosettes, usually with an angular bend in the 

 shaft ; with a triangular upper tooth 60 /a long, about the 

 same length as the up))er alae, which latter are very wide. 

 AVith the lower tooth oblong, 12-8 /a high, with a slightly 

 convex edge ; in one of the specimens this edge is produced 

 into a denticle. 



A smaller kind of anisochelae palmatge, 47 /x long and 17 yu, 

 broad, at the upper end, with a long oval tooth 20 /x long 

 extending below the alai. 



Trichodragmata, 62xl2yu., the trichites being very fine, 

 sharj)ly pointed oxeas. 



There are three fine specimens of this sj^ccics, the largest 

 forming a thick fiabellate body 17 cm. high, 11 cm. broad, 

 and 7 cm. thick. 



The mammilla3 are on an average about '75 cm. in height, 

 and 1 cm. in diameter at the base. The new si)ecies bears a 

 very close resemblance to Mycale magellanica, liidley, wiiich 

 likewise has a nuimmillated, finely reticulate surface and 

 glistening skeletal fibres, but here the surface is smooth and 

 not hispid, and the megascleres are styles, or sul)tyles, such 

 as are normally found in the genus Mycale. The microscleres 

 also are different in the two species. 



A second species of Mycale with oxeate megascleres is 

 Ann. cD Ma,j. N. Hist. Ser. 7. Vol. xx. I'J 



