226 



Genus Tetilla. 



Tetilla bonaventura, 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 1.5 

 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'), 1085 X 31 ,". 



Anatriaenes (Fig. 2c, c'), rare, rhabdome 8000 X 7m, enlarg- 

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

 cladut 60 n, chorda go /n. 



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

 same dimensions as the anatriaenes, from which they have been 

 derived- 



Protrisenes (Fig- 2f, f) 2720 X 12.5 /^ with terminations of 

 extreme tenuity; length of cladus 100 /<, chorda 60 /<» 



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

 protriaenes figured in fig. 2f. 



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

 25 fi, the other two each 8 // in length- 



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



Locality — Fals^ Bay, 22 fathoms. 



The single specimen is 4 cm. in height and 5 cm- in diameter 

 in horizontal plane. The new species resembles T. coronida 

 Sollas, and T. pedifcra Sollas in having anamonaenes, but T- 

 pedifera has no microscleres : the anamonaene of T. coronida pro- 

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

 sent species from a reduced anatriaene, the shape of the anarnon- 

 aene 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, SoUas [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 specnnen 

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

 a solid sphere segment or low circular dome with a flat 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 m the 

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

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



