REPORT ON THE DEEP-SEA KERATOSA. 69 



distinguished from the other species externally in the arenaceous and coarsely-granular 

 appearance of the white surface, due to the large, densely crowded, Globigerina shells 

 which compose the two thick, parallel, dermal plates. The dry sponge, therefore, is very 

 stiff, friable and fragile, arenaceous and inelastic. In the wet state it is extremely 

 flaccid, and may be easily torn. The outline of the leaf is usually ovate or obliquely 

 elliptical ; its thickness is considerable, and nearly equal throughout its whole extent, 

 about 2 to 3 mm., sometimes 4 mm. or more. The diameter of the leaf is usually between 

 40 and 60 mm., sometimes 80 to 90 mm., or even more. The tapering proximal part is 

 prolonged into a conical pedicle of variable thickness, the basal insertion of which is often 

 bulbous. Sometimes the thick pedicle is prolonged as a prominent median rib in the 

 proximal half of the leaf, gradually tapering distally. The coarsely-granular surface of 

 the leaf usually exhibits more or less distinct traces of the concentric zones which are 

 characteristic of Stannophyllum zonarium, but they are never so regular nor so distinct 

 as in that species, and sometimes they are absent altogether. 



A few specimens of this species were distinguished by the production of one or two 

 surface lobes arising from one or both sides of the leaf (PI. I. fig. 5B). This production 

 forms a transition to the genus Stannarium (PI. III. figs. 6-14). 



Stannopliyllum globigerinum is the fittest for anatomical examination of all the five 

 species of this genus, for the greatest part of the skeleton, viz., the calcareous 

 Globigerina ooze, is easily dissolved in hydrochloric acid. The remaining portion of the 

 body is partly a scarce maltha (sometimes containing ova), partly a very loose felty mass, 

 composed of irregular bundles of spongin-fibrillas, interwoven in all directions, and of the 

 branched canals of the sponge, which run between the brown network of the symbiotic 

 Hydroid. The reticular hydrorhiza of this latter is usually richly developed, and may 

 be more easily isolated than in the other species of the genus (PI. II. fig. 5). In a few 

 specimens the hydranths (y") and gonangia (g) were well preserved, and could be 

 recognised as belonging to two distinct species of Stylactella (Stylactella spongicola, 

 PI. II. fig. 6 ; and Stylactella abyssicola, fig. 7). 



Genus 10. Stannarium, 1 n. gen. 



Definition. — Stannomidaj with branched lamellar body, forming vertical plates, which 

 arise as lateral branches from a primary flabelliform body. 



The genus Stannarium comprises those Stannomidae in which the body is composed 

 of several vertical leaves, which are either free or growing together. There can be no 

 doubt that this peculiar form has originated from Stannophyllum by lateral budding, and 

 that two opposite of these vertical wings are the halves of the primary flabelliform leaf 



1 Stannarius = Cementing or soldering workman. 



