226 



Genus Tetilla. 



Tetilla bonaveutura, sp. n. 



Plates II and III, fig. 2. 



Sponge shaped like a mushroom with a thick stem. The dome- 

 shaped upper surface finely hispid, with several small oscules i K 

 mm. in diameter- Colour a dirty greenish grey. 



Spicules Megascleres.-Oxea (Fig. 2a) 4200 X 48 /«, almost 

 straight, slightly aniso-actinate, sharp-pointed. Smaller curved 

 oxea and styles (Figs. 2b^ b'), 10S5 X 31 ". 



Anatri^nes (Fig. 2c, c'), rare, rhabdome 8000 X 7/«, enlarg- 

 ing up to 12.5 u in width at junction with cladome ; length of 

 cladus 60 u, chorda 90 ^i. 



Anadiaenes (Fig. 2d), abundant, and anamonsenes (rare), of the 

 same dimensions as the anatriaenes, from which they have been 

 derived- 



Protriasnes (Fig- 2f, f) 2720 X 12.5 /< with terminations of 

 extreme tenuity ; length of cladus 100 /.i , chorda 60 //. 



Frodiienes (Fig. 2g) of approximately similar dimensions to 

 protrisenes figured in fig. 2i. 



Trichodal protriaenes (Fig. 2h), rhabdome 190 /n, one cladus 

 25 fi, the other two each 8 n in length. 



Microscleres. Sigmaspires (Fig. 2k), T1.5 «. 



Locality- — False Bay, 22 fathoms. 



'I'he single specimen is 4 cm. in heigh* and 5 cm- in diameter 

 in horizontal plane. The new species resembles T. coronida 

 SoUas, and T. pcdifcra Sollas in having anamonaenes, but T- 

 pcdifcra has no microscleres : the anamonasne of T. coronida pro- 

 bably results from the reduction of a protriaene, but in the pre- 

 sent species from a reduced anatrisene. the shape of the anamon- 

 sene being very different in the two cases. 



Another characteristic feature of the new species is the occur- 

 rence of the anadiaenes. 



Tetilla casula, Carter. 



Plate II, figs. 3, 3a. 



1871, Tethya casula, Carter [1], p. 43. 



1888, Tetilla casula, SoUae [11], p. 99, pi. IV., figs. 1-9. 



The one example of this species occurring in the present collec- 

 tion presents a very different appearance from the type specimen 

 figured by Carter [i], pi. iv- fig- i. The former has the shape of 

 a solid sphere segment or low^ circular dome with a fiat under 

 surface. It seemed, at first sight, as though the specimen were 

 a piece sliced off from a spherical sponge- Dr. Gilchrist remem- 

 bered, however^ the sponge being brought to the surface in the 

 condition in which he sent it. The flat base is 5 cm. in diameter, 

 and the height 1.7 cm. The convex surface, over the lower half of 



