128 Mr. R. Kirkpatrick. Ona Remarkable  [Aug. 16, 
1 mm. deep, and 2 mm. broad, is divided into two nearly equal parts by a 
narrow vertical band of scales. The rounded or polygonal meshes of the 
network of triradiates are about 0°2 mm. in diameter, and one pore is 
contained in each mesh (Plate 10, fig. 8). 
The pores lead into sub-dermal spaces, which either abut directly on to — 
masses of flagellated chambers fillimg in the surface-meshes of the main 
skeletal network just below the pore-area (Plate 10, fig. 5), or are continued 
into canals passing into the sponge. 
The flagellated chambers are oval or spheroidal, and of large size, being 
about 65x50 in long and short diameters. Minute prosopyles were 
visible in some instances, also a circular apopyle, about 20 mw in diaieter. 
The chambers line the walls of tubular anastomosing canals, occupying 
the spaces of the main skeleton, just as in Minchinella lamellosa, Kirkp. 
(Plate 11, fig. 13). The exhalant canals pass up into the floor and walls 
of the single terminal exhalant canal or cloaca, which opens by the oscule. 
The cloaca is from 1 to 2 mm. deep. 
The structure of the collar-cells and of the other soft tissues was not 
to be made out clearly, owing to the sponges not having been properly fixed 
at the moment of capture, and as there is some prospect of getting fresh 
material suitably preserved, no attempt has been made to describe the cell- 
structure. 
The Skeleton. 
The skeleton will be described under three heads, viz. : (1) the main body- 
skeleton; (2) the poral and sub-dermal spicules; and (3) the dermal 
scales. 
The main skeletal framework has a structure wholly unique in sponges. It 
is constructed of a strong network of solid calcareous fibres, entirely devoid 
of spicules, either in the axis of the fibres or on the surfaces of the same. The 
strands of this remarkable network vary greatly in shape and size, but they 
are mostly laminate, v.e. they are thin in proportion to their breadth. An 
average-sized strand measured 375 w in length, 150 w in breadth, and 45 w in 
thickness, and the oval mesh which it bounded was 375 w long and 150 pw 
broad; but the meshes and strands may be considerably larger, viz., up to 
500 long. Usually, the meshes are longer in the vertical plane of the 
sponge than in the horizontal (Plate 10, figs. 4, 7, 9). 
At the surface of the body the skeleton tends to form longitudinal flanges 
with free edges which slightly overlap, and which support the dermal 
skeleton. 
The strands show a laminate construction, as if they had been laid down 
