36 R. KIRKPATRICK. 



MYCALE MAGELLANICA. 

 (Plate XX., fig. 2.) 



1881. Esperia magettanica Ridley (15a. p. 117). 



1887. Esperella magellanica Ridley and Dendy (15. p. 67). 



1905. Mycale magellanica Thiele (23. p. 442). 



The ' Discovery ' collection contains one large piece, much damaged. The figure 

 (XX. 2) shows the smooth surface in contrast to the hispid surface of the new species 

 M. acerata described below. 



The specimen was dredged near Winter Quarters, from No. 10 hole, 130 fms. 



The species is also recorded from Sandy Point, 7-10 fms. ; from Otter Island, 

 Patagonia ; and from east of Cape Virgins. 



MYCALE ACERATA. 



(Plate XX., figs. 1, la-b, and Plate XXIV., figs. lOa-e 1 .) 

 1907. Myxilla acerata Kirkpatrick (10a. p. 280). 



Sponge large, massive, with numerous small rounded mammillae ; surface finely 

 reticulate and finely hispid. Colour, creamy-white in spirit. Consistence, soft, the 

 tissues being easily torn. The flesh reddish (but soon decolorised), and showing the 

 glistening white strands of the skeleton. 



Oscules in form of wide thin-walled cylindrical chimneys with rather jagged upper 

 edges, about 1 cm. in height, and 1-2 cm. in diameter. 



Skeleton. Ectosomal : A network of triangular meshes formed by bundles of 

 oxeas, the strands being from '35 mm. thick and the meshes about '5 mm. across. 

 Main skeleton formed of long thick anastomosing fibres which attenuate gradually 

 from 1 5 mm. 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 16' 25 M, slightly curved, rather abruptly 

 pointed at one end, and more tapering at the other. These oxeas form the fibres, and 

 also are gathered into bundles, one spicule in length, of parallel oxeas, scattered in 

 the choanosome. 



Microscleres. Large anisochelae palmatae, 105 x 50 /u, separate or in rosettes, 

 usually with an angular bend in the shaft ; with a triangular upper tooth 60 M long, 

 about the same length as the upper alae, which latter are very wide. With the 

 lower tooth oblong, 12'8/u high, with a slightly convex edge; in one of the 

 specimens this edge is produced into a long denticle (XXIV. 10 c). 



A smaller kind of anisochelae palmatae (fig. lOd, d 1 ), 47 /* long and 17 M broad, at 

 the upper end, with a long oval tooth 20 M long, extending below the alae. 



Trichodragrnata, 62 X 12 n, the trichites being very fine, sharply-pointed oxeas. 



There are three fine specimens of this species, the largest forming a thick 



