1881.] 



THE SURVEY OF H.M.S. 'ALERT.' 



125 



Hab. Trinidad Channel, near Madre-de-Dios Islands, off S.W. 

 Patagonia, 30 fathoms. 



Obs. The two already described species, Halichondria aspera 

 and Isodictya rudis, Bowerbank, both from the Straits of Malacca, 

 possibly merely varieties of one species, together with Tedania suc- 

 toria, Schmidt, from Iceland, resemble our species in important 

 points. It is also noteworthy that Schmidt refers (Spong. atl. Geb. 

 p. 43) to a shapeless white specimen of a Tedania from llio de 

 Janeiro, to which he gives no name. Looking at the locality and 

 at this description, one would not be surprised to find that it proved 

 to be our species. 



The two Malacca species have a most interesting relation to the 

 rest ; for with the terminally microspined heads of the cylindrical 

 spicule, characteristic of the Mediterranean Tedanice, they combine 

 a very marked roughening of the fine acerate — an irregularity of 

 the surface which is only possible to make out, in the case of T. tenui- 

 capitata, with very good light, and then not always, and which is, 

 so far as I am aware, peculiar to the acerates of this genus, being 

 wholly distinct from spination or " microspination." 



Tedania suctoria, Schmidt, has cylindricals with two smooth heads, 

 as in our species ; but they are not terminally pointed as here. It 

 is probably the most nearly allied of described species. Its spicule- 

 characters, for comparison with those of T. tenuicapitata, are : — 



Smooth Acuate Spicule. 



Cylindrical Bicapitate.. 



Fine Acerate 



Skeleton 



T. mctoria. (Iceland.) 

 tapering very gradually 

 from head. Size •5325 

 by -OlbSZ mm. 

 Heads oval, rounded off 

 terminally. Size '3357 

 to -38 by 008445 mm. 

 " Surface-roughness gene- 

 rally perceptible. Size 

 •2924 by -00285 mm. 



( Main-skeletou fibres more 

 compact. Dermal cylin- 

 dricals radiate more re- 

 gularly ; bundles larger 



I and less distinct than in 



I, the other species. 



< 



T. tenuicapitata. 

 (S.W. Chili.) 



Beginning to taper about 

 (3 diam. fromend. Size 

 •38 by -01267 mm. 



Heads shghtly oval, 

 pointed. Size -2787 

 by •006334 mm. 



Surface-roughness rarely 

 perceptible with cer- 

 tainty. Size •SIG by 

 •002114 mm. 



Skeleton-fibres as loose as 

 possible. Dermal cy- 

 lindricals in distinct 

 bundles, radiating each 

 from a separate point. 



Amorphina sp. inc. 



A minute, thin, incrusting patch on the worm-tube which bore 

 Alebion proximum. It is white; and the sarcode is granular, but almost 

 colourless ; the spicules are smooth, sharply bent acerates, ending 

 rather abruptly in points, and resembling those of A, genetrix, 

 Schmidt, but far smaller, and massed in flattened tracts. 



Hab. Sandy Point, 7-10 fathoms. 



