REPORT ON THE HEXACTINELLIDA. 101 



degenerated in several points, as may be seen in tlie preponderance of uniaxial spicules, 

 and also in the absence of a special root-tuft. 



Character of the Genus. — The somewhat thick-walled cup- or bowl-shaped body is 

 firmly attached to the substratum by means of a more or less long and compact cylindrical 

 stalk. The sharpened circular oscular margin usually bears a membranous, perpendicular, 

 annular fringe, though occasionally naked. The external surface appears smooth and 

 sometimes meshed. On the internal surface the numerous efferent canals open, through 

 roundish apertures of variable size, directly into the large gastral cavity. The parenchyma 

 includes oxyhexasters and discohexasters of variable form and size. The dermal 

 membrane contains small rough tetracts and pentacts, and sometimes also diacts, which 

 are blunted terminally or thickened in club-shaped fashion. The gastral membrane 

 contains roughened pentacts. 



1. Crateromorpha meyeri, Gray (PI. LXL). 



Near Zebu, Philippine Islands {Station 209), from a depth of 95 fathoms and a 

 blue mud ground, several well-preserved specimens of Crateromorpha meyeri were 

 obtained. 



The sponges are 10 to 12 cm. in height, and of a beautiful wine-glass-like form. An 

 irregular expansion (basal plate) attaches the sponge to the firm substratum, and the 

 cylindrical stalk, about 5 cm. in length and about as thick as one's little finger, is con- 

 tinued through a trumpet-like enlargement into a widely open bulging cup, about 5 cm. 

 in breadth. The wall of this cup is inferiorly about 2 cm. in thickness, but becomes 

 narrower upwards and finally ends in a delicate, thin, ti\insparent, straight or slightly 

 outwardly curved lamellar fringe, with a sharp edge, which measures 4 mm. in height, 

 and about 0"5 mm. in thickness. The external dermal surface of the whole sponge is 

 smooth, but through the fine rectangular lattice-work of the dermal membrane the 

 irregular roundish cavities of the afferent canals may be seen (PI. LXL fig. 1). On the 

 much firmer internal surface there are numerous roundish openings of varying width. 

 These belong to the eS"erent canals. The smaller apertures in the neighbourhood of the 

 lattice-work are still covered by the gastral membrane, but the larger open freely. 

 Inferiorly the openings of the efferent system of canals become larger, so that finally, 

 at the foot of the gastral cavity, only more or less narrow septa remain between them. 

 (PI. LXL fig. 2). The larger septa extend radially from the centre towards the lateral 

 wall, and produce a radially symmetrical division into four, which recalls a similar con- 

 dition in species of Hyalonema. In longitudinal sections the relation of the afferent 

 and efferent canals is very distinctly seen, and between them the much folded layer 

 of ciliated chambers (PI. LXL figs. 2, 3). 



In PI. LXL fig. 1 an attempt is made to reproduce the peculiar grey-yellow colour, 



(ZOOL. CHALL, EXP. — PART LHI. — 188G.) Ggg 21 



