16 PERCY SLADEN TRUST EXPEDITION 
(3) Small triradiates of the dermal skeleton (Plate 5, fig. 4, 6); irregular, but 
probably really equiangular ; with slender, irregularly curved rays, often unequal in 
length and sometimes blunt at the apex. One of the rays (x) is frequently bent inwards, 
out of the tangential plane. Rays measuring, say, about 0°1 by 0°0055 mm. 
(4) Quadriradiates of the gastral cortex; equiangular and typically equiradiate ; 
with long, straight, slender facial rays, fairly sharply pointed and measuring about 
0176 by 0°0125 mm.; with short, slightly crooked apical ray, not hooked and about 
0075 mm. long. 
(5) Quadriradiates of the larger exhalant canals. Similar to (4) but frequently 
with very much longer, almost or quite straight apical rays, measured up to 0°29 mm. 
in length. 
(6) Quadriradiates of the oscular collar; sagittal, but otherwise resembling those of 
the gastral cortex further in. 
As in P. heteroraphis, the position of the nuclei of the collared cells is basal. The 
ectosome contains large numbers of pigment cells filled with minute granules of a golden 
brown colour. Similar, but less numerous pigment granules occur in the ectosome of 
P. heteroraphis, probably also in special cells. 
This species is distinguished from P. heteroraphis chiefly by its remarkable external 
form. 
Register No., Locality, dc. XxXvi., Cargados Carajos, 31.8.05, 12 fathoms. 
Family Leucaltide Dendy and Row MS. 
Sponge colony tubular and ramified, or even anastomosing, with many oscula; or 
individualized, with large central cavity and single osculum. Wall of colony composed 
of at least two distinct layers, viz. a dermal cortex with a strongly developed skeleton 
of tangential radiates, and a chamber layer with skeleton greatly reduced or even 
absent. A thin gastral cortex or membrane may or may not be present. Skeleton 
composed, mainly at any rate, of equiangular radiates. No subgastral sagittal radiates. 
Nuclei of collared cells probably always basal. 
Genus Leucautis* Haeckel (emend.). 
Sponge colony tubular, ramified and anastomosing. Flagellate chambers elongated 
and branched, more or less radially arranged around the central gastral cavity. 
I am now convinced that Bidder [1898] was quite right in considering this genus 
to be closely related to the radiate Homoccela as represented by Dendya; its apparent 
affinity with the Amphoriscidz is evidently due to convergence. 
8. Leucaltis clathria Haeckel. 
(Plate 2, figs. 1, 2.) 
Leucaltis clathria Haeckel [1872]. 
Heteropegma nodus gordw Poléjaeff [1883]. 
* This genus is generally known under Poléjaeft’s name Heteropegma, but Leucaltis has priority. 
