176 



whicJi it contracts, and then expands gradually to the sum- 

 mit. The height is 18 cm., breadth 8.5 cm., and thickness 

 4.5 cm., so that the club is slightly flabelliform ; the area of 

 the rounded summit is 5 x 4 cm. 



The smaller specimen has been broken off sharp from its 

 attachment, exposing excurrent canals i mm. in diameter ; its 

 shape is more cylindrical than the first, and resembles a mile- 

 stone ; its height is 7 cm., and its diameter 4 cm., the diameter 

 at the base being 2.4 cm., and at the summit 3x2 cm. 



Locality : O'Neil Peak, Natal Coast, bearing N.N.W. i W., 

 distant 8 miles ; depth, 55 fathoms ; bottom, broken shells. 



Family Desmanthids. 



Monanfhus, ijen. iidv. 



DcsuuintliidiV in which the skeleton is formed of monocrepid 

 desmas of the coniiiioii f\'pi\ separate or joined together, and of 

 monaxon megascleres. 



Monan' hus plumosus, sp. n. 

 I'latc iv.. rtijp. (1, 6.1-c. Fij^s. 7, 7a, h. 



Description of the type spechiien (Fig. 7, 7a, b). Sponge 

 forming a thick white crust, firm but compressible, with several 

 round oscules flush with the surface. 



Skeleton composed of plumose columns extending from base 

 to surface, and fcn'ined of bundles of oxeas (mostly) and styles ; 

 between the columns monocrepid desmas isolated and separate 

 or here and there loosely articulated with each other. 



Spicules. — Desma, with smooth epirhabd 140x40 f, often 

 bifurcating at each end with flattened branches, sharp-edged or 

 expanded into flattened articular surfaces; crepidial axis 80 /«. 



Oxea, 480 X 25 /', smooth, curved, sharp-pointed. 



Stvle, 600 X 28 /', slightly curved. 



Thiele (Ueber Cniinbc cniinbc (O.S.) Archiv. f. Naturgesch, 

 1899, p. 89) expresses doubt whether Topsent's genus Dcs- 

 niaitiliiis is Lithistid or Monaxonid; and possibly the posi- 

 tion of MoiuiiifJiiis would be subject to the same doubt. 

 The desmas of Di'siiiaiitliifs are tetracrepid, and those of 

 Moiidiifliiis monocrepid ; in both instances the desmas seem 

 to be of the ordinary Lithistid type, though in the 

 case of MoKintliiis they often appear to be undergoing 

 degeneration ; even in isolated spicules, however, well formed 

 articular surfaces often persist, clearly showing that these 

 spicules are derived from forms which were part of an 

 articulated Lithistid skeleton. In the deeper parts of the type 

 specimen, and in the second specimen of M. plumosus, where 



