352 THE VOYAGE OF H.M.S. CHALLENGER. 



The slightly irregular dictyonal framework consists of moderately thick beams, 

 somewhat uniformly beset with fine tubercles. The nodes of intersection exhibit no 

 thickeninsj, and on the boundina; surface slender tubercle-like bosses of moderate length 

 project freely (PI. CI. fig. 3). The dermal membrane contains rough pentacts disposed 

 I'egularly so as to form square meshes. In these sj)icules, the four uniformly long tangential 

 rays end in a knot-like swelling, while the much longer jiroximal radial, which becomes 

 narrower inferiorly, is simply rounded off or pointed. The parenchyma includes delicate 

 oxyhexacts with somewhat undulating rays, which sometimes divide, and may also 

 exhibit thickened points of intersection (PI. CI. figs. 5, G). More frequently sphsero- 

 hexasters occur of variable size, and with a variable number of terminal rays. The 

 principal rays are either moderately short, bearing six to eight knobbed terminals, about 

 three times as long, somewhat markedly divergent and slightly curved (PI. CI. fig. 8), or 

 they are so shortened that they appear rather as a spherical thickening of the node of 

 intersection. In the latter form the numerous, long knobbed terminal rays look like 

 simple radii from a s^Dherical centre (PL CI. fig. 7). 



0. Schmidt notes that the form was dredged at Havanna, West Indies, from a depth 

 of 158 fathoms. 



Genus 4. Myliusia, Gray (PI. CIIL). 



1859. Gray, Pioc. Zool. Soc. Lond., vol. xxvii. p. 437 ; Ann. and Mag. Nat. Hist., ser. 3, vol. v. 



p. 495 (Mi/Iiusia calloajcdhes). 

 1867. Graj', Proc. Zool. Soc. Lond., p. 492. 



1869. Bowerbank, Proc. Zool. Soc. Lond., pp. 66, 334 {Myliusia grayi). 



1870. 0. Schmidt, Grundziige einer Spongienfauna des Atlant. Gebiet. 



1872. Gray, Ann. and. Mag. Nat. Hist., ser. 4, vol. i.x. p. 442. 



1873. Carter, Ann. and Mag. Nat. Hist., ser. 4, vol. xii. p. 349. 

 1875. Carter, Ann. and Mag. Nat. Hist., ser. 4, vol. xvi. p. 1. 



1875. Marshall, Zeitschr. f. wiss. Zool., Ed. xxv., Suppl. 



1876. Marshall, Zeitschr. f. wise. Zool., Bd. xxvii. 



1877. Carter, Ann. and Mag. Nat. Hist., ser. 4, vol. xix. p. 121. 



1877. Sollas, Ann. and Mag. Nat. Hist., ser. 4, vol. xix. p. 43 {Mijliusia gyayi) ; and voh xx. 

 p. 285. 



1877. Zittel, Abhandl. d. k. Baier. Akad. 



1878. Marshall and Meyer, Mittheil. d. Zool. Mus. zu Dresden, I'.d. ii. p. 261. 



1879. 0. Schmidt, Spoogien der Meerbusens von Mexico, vol. i. 



1880. O. Schmidt, Spongieu der Meerbusens von ]\Iexico, vol. ii. 

 1882. Weltner, Beitrage zur Kenntniss der Spongien. 



History. — In 1859 Gray' described and figured a new sponge procured from the West 

 Indies, which he regarded as representative of a new genus, and named Mj/Iiusia, with 

 the specific name callocyathes.- The generic title was given in honour of Christlob 

 Mylius, who was the first] to descrilie the singular Unibellularia groenlandica. The 



' Proc. Zool. Soc. Lond, p. 439 ; A iin. and. Mag. Nat. Hist., ser. 3, vol. v. p. 497. 

 - Properly, callocyathus, I'roiii y.iix6o:, a cui). 



