354 THE VOYAGE OF H.M.S. CHALLEN(}ER. 



between the two species Mylinsia {Iplikcon, Bowerbank) callonjatlnis, Gray, and 

 Myliusia grayi, Bowerbank, but without further inquiry have assigned both to the 

 same genus Myliusia — a generic name which, after what has been said, ought to be 

 applied to Myliusia callocyathus, and not to Myliusia grayi, Bowerbank, in case the 

 latter of the two species does not belong to the same genus. 



In 1873 Carter' established a characteristic difference between Myliusia callocyathus, 

 (!ray, and Myliusia grayi, with respect to the rosettes. In Myliusia callocyathus, the 

 " rosettes are many rayed; rays of equal length, capitate, flexed, and grouped en fleur- 

 de-lis, or occasionally with straight and capitate rays ; " in Myliusia grayi " the 

 rosettes are many rayed, rays of equal length, straight, capitate." 



In the memoir which Marshall published in 1876 on the affinities of the Hexactin- 

 ellida- he seemed inclined to identify Myliusia callocyathus, Gray, with Dactylocalyx 

 crispus, 0. Schmidt. 



In the description of Myliusia grayi, Bowerbank, which Carter gave^ in 1877, he 

 notes that^ " although Myliusia grayi presents the convoluted cerebriform appearance of 

 Myliusia callocyathus, yet its minute structure is totally diff'erent, inasmuch as the knots 

 or junctions of the fibre in the latter are solid and round, not hollow and lantern-shaped 

 as in Myliusia grayi." 



In his studies on fossil sponges Zittel'^ places Myliusia grayi — 2:)robably with exclusion 

 oi Myliusia callocyathus, Gray — along with Dactylocalyx, Stutchbury, AnAPeriphragella, 

 Mar^all, in his family of the Mfeandrospongidaj, " in which the sponge body consists of 

 meandering, intertwining, and anastomosing thin-walled tubes or laminse, the canal 

 system absent or scarcely developed, the intercanal system, on the other hand, present. A 

 covering layer is wanting, or forms a coherent siliceous skin on the surface." 



In a report from the Dresden Zoological Museum (1878), Marshall and Meyer 

 accurately described a new sponge from the Philippines as Myliusia zittelli, Marshall and 

 Meyer. But since this form is doubtless closely related not to Myliusia callo- 

 cycdhus, but to Myliusia grayi, Bowerbank, we shall not at this stage take it into 

 consideration (see Aulocystis). The species in question was found by 0. Schmidt among 

 the West Indian sponges of the American Expeditions. 



1. Myliusia callocyathus. Gray (PI. CIIL). 



Specimens of this elegant species were procured from three stations by the Chal- 

 lenger Expedition, but of these none attains the size of the example described by J. E. 

 Gray, and figured in the Proceedings of the Zoological Society of London, 1859, pt. xvi. 



1 Ann. and Maij. Nat. Hist., ser. 4, vol. xii. p. 358. - Zeitschr.f. wiss. Zool, Bd. xxvii. pp. 113-1.36. 



3 Ann. and Mag. Nat. Hist., .ser. 4, vol. xix. pp. 120-131. ■• Loc cit., p. 128. 



° Abhandl. d. k. Baier. Acad., p. 38, 1877. 



