Dr. J. E. Gray on two new Forms of Sponges. 497 



existence of two bodies always found together, and unknown in any 

 other form, instead of their being regarded as parts of the same 

 animal. 



The axis of this body has many characters in common with the 

 body which is called a Sponge described by Mr. Stutchbury in our 

 Proceedings for 1841, p. 87, as mentioned above, under the name 

 of Dactylocalyx pumiceus, and which has been more lately described 

 under another name by M. Valenciennes ; a very fine specimen of 

 this is in my collection ; but in this sponge it is .the outer surface 

 which is marked " with deep sinuosities radiating from the root to 

 the outer circumference." 



We have lately received from Dr. William MacGee of Belfast a 

 very curious specimen of a silicious sponge?, which is also allied to 

 the Dactylocalyx and MacAndrewia, but so distinct in its form and 

 structure that I am inclined to regard it as the type of a new genus, 

 which may be called 



MYLIUSIA, 



Sponge ? silicious, funnel-shaped, fixed by the base ; the upper 

 surface smooth, marked with numerous minute perforations placed 

 in nearly parallel grooves radiating from the centre to the circum- 

 ference, and with numerous large, oblong, rather unequal-sized per- 

 forations, which are fringed on the lower side with a high wall of 

 a similar structure to the rest of the sponge ; these edges of the 

 cavities causing the under surface to be covered with unequal irre- 

 gular shaped tubes of nearly the same length, and more or less con- 

 fluent together : some of these tubes are simple and subcylindrical, 

 others are expanded and more or less crumpled on the edge around 

 the cavity, so as to end in two, three, or even four, more or less 

 circular mouths. 



MYLIUSIA CALLOCYATHES. 

 Hab. West Indies (Dr. MacGee). 



Dr. Bowerbank informs me that the silicious spicula of this sponge 

 are very different from those of Dactylocalyx pumiceus. As he 

 is working on that subject, I leave the peculiarities for him to de- 

 scribe ; but I should not be in the least surprised if the genera Mac- 

 Andrewia^ Myliusia, and Dactylocalyx should all prove to be a 

 peculiar family of zoophytes rather than sponges. If these bodies 

 are sponges, they will form a family in that group, which may be 

 named MacAndrewiadce, characterized by the peculiar form and 

 structure of the axis, the distinctness of the bark, and the position 

 of the oscules or cells. 



The structure of the base of Dactylocalyx and of the spicula which 

 are found in the interspaces of the network are figured by Mr. 

 Quekett in his ' Lectures on Histology.' 



I have named this genus after Christlob Mylius, who first de- 

 scribed the curious zoophyte since called Umbellularia grcenlandica ; 

 and I think that any one who reads his simple and plain account 

 of the animal in his letter to Haller, and the account of the same 



Ann. % Mag. N. Hist. Ser. 3. Vol. v. 33 



