176 



whicli 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 tlie club is slightly fiabelliform ; the area of 

 the rounded summit is 5x4 cm. 



The smaller specimen has been broken oil sharp from its 

 attachment, exposing excurrent canals j 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'Xeil Peak, Xatal Coast, beariiig N.N.W. ^ W., 

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



Family Desmanthidag. 



Monanthus, .^cn. nov. 



DesiHciniliida in which the skeleton is formed of monocrepid 

 desmas of the couuuoii type, separate or joined together, and of 

 monaxon megascleres. 



Monan'hus plumosus, sp. n. 

 I'lalc iv., tiijs. 6, 6;(-c-. Ki.^s. 7, "a, b. 



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

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

 round oscules flush with the surface. 



Skeleton composed of plumose cohmius extending from base 

 to surface, and formed 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 t^, often 

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

 ■expanded into flattened articular surfaces; crepidial axis 80 /'. 



Oxea, 480x25 /', smooth, cur\ed, sharp-pointed. 



Style, 600x28 /', slightly curved. 



Thiele (Ueber Cnniibc cnitiibc (C).S.) Aichiv. f. Naturgesch, 

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

 tiiniitliits is Lithistid oi" Monaxonid; and possibly the posi- 

 tion of MoiKiiilliiis would be subject to the same doubt. 

 The desmas of Dcsiiidiithiis are tetracrepid, and those of 

 MoiidiifliifS monocrepid; in both instances the desmas seem 

 to be of tlie ordinary Lithistid type, though in the 

 case of Moudiifliiis Ihey often appear to be undergoing 

 degeneration ; eyeii in isolated spicules, howeyer, 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 m tlie si-cond specimen of M. plumosus, where 



