REPORT ON THE HEXACTINELLIDA. 159 



being hidden by a spherical central thickening, from which the long terminals directly 

 arise, resulting in a many-rayed form. 



In certain regions, and especially below the external skin, in the subderinal space, 

 there is a tolerably abundant occurrence of those eight-rayed discohexasters, which were 

 already described in Rhahdocaly2)tus mollis. Here also there are eight medium-sized 

 principals not exactl}^ round, but somewhat angular. These form approximately equal 

 angles with the central node, which is beset with roundish tubercles. Terminally the 

 principals tlivide into three to four fine, long, diverging terminals, which bear on their 

 extremities small, toothed, transverse discs. 



We have also to note the quite isolated occurrence of very small delicate disco- 

 hexasters (PL LXV. fig. 4), in which the expanded ends of the principal rays bear 

 numerous fine terminals, with transverse discs on their extremities. 



The dermal skeleton includes medium-sized hypodermal oxypentacts, in which the 

 long, smooth, occasionally somewhat curved rays, are roughened towards the pointed 

 extremities. The dermal membrane itself contains a large number of pentacts, tetracts, 

 diacts, and occasionally monacts, in which the rough straight rays, beset with small 

 pointed spines, are rounded off at their outer ends, or provided with blunt points 

 (PL LXV. figs. 7, 8, 9). At the middle of the diacts and at one end of the monacts, 

 four or five ci'uciately disposed hemispherical tubercles (or sometimes two in one axis) 

 project laterally as rudiments of the undeveloped rays (PL LXV. figs. 7, 8). 



The gastral skeleton, and that of the skin which lines the wide efi"erent canals, 

 consists exclusively of comparatively large oxyhexasters in the usual disposition. The 

 weakly developed straight rays, which are of approximately equal length, have an 

 irregularly tubercled or roughened surface (PL LXV. fig. 10). 



There are no marginalia in this species. 



Genus 7. C rater omorpha. Gray (Pis. LXL-LXIII., LXVIL, LXVIIL fig. 2). 



1872. Carter, Ann. and Mag. Nat. Hist., vol. x. p. 110 {Crateromorpha mei/eri). 



1872. Gray, Ann. and Mag. Nat. Hist., vol. x. p. 13G. 



1873. Carter, Ann. and Mag. Nat. Hist., vol. xi. p. 275. 



1873. Carter, Ann. and Mag. Nat. Hist., vol. xi. p. 349. 



1874. Graj', Ann. and Mag. Nat. Hist., vol. xiii. p. 284. 



1875. Carter, Ann. and Mag. Nat. Hist., vol. xvi. p. 1. 



1875. Marshall, Zeitscbr. f. wiss. ZooL, Bd. xxv., Suppl., p. 112. 



1876. Marshall, Zeitschr. f. wiss. ZooL, Bd. xxvii. p. 113. 



1877. Zittel, Mitth. d. Baler. Akad., xiii. p. 1. 



History. — Among the sponges which Dr. A. B. Meyer sent home from Zebu (one of the 

 Philippine Islands), to the British Museum, there is an oval cup- or bell-like form with 

 a round but comparatively slender stalk. This form was distinguished by Gray as 



