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



Dactylocalyx j^umicetis, Stutchbury, was found in the neighbourhood of Barl)ados 

 at a depth of 103 fathoms; Dactylocalyx suhglobosus, Gray, near St. Lucia, in 11 G 

 fathoms, and also to the north-west of Havanna in 190 fathoms. 



As a new species Schmidt described a drinking-horn -shaped Dactylocalyx {Dactylo- 

 calyx potatorum) dredged from a depth of 190 fathoms near St. Lucia. Its wall measured 

 1-5 to 2-5 cm. in thickness, and consisted of a very light and fragile lattice-work of fine 

 tubes. It also exhibited external as well as internal deep pittings, the openings of 

 which alternate on the surfaces of the walls, and appear on the inner side to be arrangccl 

 in lou'i-itudinal rows. Further, the form described by Gray as Myliusia callocyathes was 

 referred by Oscar Schmidt to the genus Dactylocalyx. 



Generic Characters. — The cup-shaped, thick-walled body exhibits both on the outer 

 and on the inner surface irregular, but generally radial ridges, and interjacent furrows. 

 Since internal furrows correspond to external ridges, the whole wall seems to be 

 folded. It consists of a system of anastomosing, but mainly radial tubes, which open 

 internally, and perhaps also externally. The system of spaces lying between these 

 anastomosing tubes is closed on the internal gastral surface. It is probable that in the 

 living form both the .external dermal and the internal gastral surface of the entire sponge 

 are covered by a flatly expanded dermal or gastral membrane. In the dermal membrane 

 pentacts occur with unpaired hypodermal ray. 



1. Dactylocalyx pumiceus, Stutchbury. 



From the original description of Stutchbury, afterwards corroborated by Bowerbank 

 and by Sollas in reference to two specimens from the Antilles Island, Barbados, and pre- 

 served in the Bristol Museum, Dactylocalyx p^imiceus has a firm, flat, cup-shaped body, 

 borne on a short, thick, massive stalk. It consists of a flat, plate-shaped roundish 

 mass, 30 cm. in breadth, as thick as a thumb, and bordered by a slightly involute, 

 slightly sinuous, rounded margin. 



The radially-disposed furrows, which are frequently interrupted, alternate on the 

 lower dermal and the upper gastral surface, and here and there exhibit dichotomous 

 division. The very fine tubular network which forms the entire body is stone-like 

 and very narrow in its meshes. The wall of the narrow tubes is composed of finely 

 tuberculate beams, without thickening at the nodes of intersection. 



Sollas found loose spicules in the parenchyma in the form of small hexacts, in which 

 the slender rays were for the most part terminally thickened, while individual rays were 

 frequently considerably elongated and somewhat curved." According to Bowerbank ' the 

 parenchyma includes oxyhexasters, with three long, slightly curved terminals on each of 

 the six short principal rays, and also discohexasters with somewhat long terminals. The 



' Proc. Zool. Soc. Lond., 1869, p. 77, pi. iii. 



