REPORT ON THE CALCAREA. 51 



curved inwards, each forming with basal ray an angle of about 110°; some of them are 

 provided with embryonic apical rays, reaching occasionally 02 to 0-3 mm. in length. 



Subgastric triradiate spicules. — Sagittal ; lateral rays either lying in the same plane or formin" 

 with one another an angle varying from 180° to 140° ; all rays of the same diameter, 

 varying from - 02 to 0'05 mm. ; basal ray straight, tapering from the base to a sharp 

 point, reaching 0'S mm. in length ; lateral rays curved, often undulating, usually half as 

 long as basal ray, often of the same length, occasionally even longer, not exceeding, 

 however, - 8 mm. 



Triradiate spicules of the parenchyma. — Either quite regular, or showing a slight tendency 

 to sagittal differentiation ; rays sharply pointed, maximum size about 1 mm., diameter 

 varying from 01 to 0"125 mm. 



Dermal triradiate spicules. — Regular, more slender than the triradiate ones just described ; 

 rays either tapering from the base to sharp points or of cylindrical form ; average size 

 of the rays - 3 mm. in length by O02 mm. in diameter. 



Colour. — Pale yellowish. 



Habitat. — Torres Strait, Australia, September 7, 1874 ; depth, 3 to 11 fathoms. 



Family Leuconid^e (Leucones) Hseckel. 



Heteroccela, whose usually round flagellated chambers communicate with the central 

 cavity not immediately but by means of its more or less deep lateral invaginations 

 (exhalent canals), the corresponding opening of the flagellated chambers being of less 

 diameter than that of the subjacent exhalent canals ; with quite irregular disposition of 

 the spicules in the parenchyma. 



Leucilla, Hagckel (sensu mutato). 



Leuconidse with flagellated chambers of an elongated, cylindrical form, recalling that 

 of the radial tubes of the Syconidse, with the skeleton of the parenchyma bearing traces 

 of a certain regularity in the arrangement of its constituent parts, owing to the disposition 

 of the subgastric and subdermal spicules directly opposite to each other. 



Leucilla eonnexiva, n. sp. (PL VI. figs, la-le). 



I can give but little information with regard to the external shape of this species. 

 There is not in the Challenger collection one complete specimen of this interesting form, 

 but only some fragments which have fortunately proved quite fit for anatomical 

 examination. Both the surfaces are rather rough ; the thickness of the walls is about 

 0"8 mm. ; the disposition of the openings of the exhalent canals is far from being so 



