Mr. H. J. Carter on a new Species o/'Tethya. 101 



sion or root 8-12ths, height of head or body ^, total height 

 14-12ths, diameter of circumference of conical expansion 1^, 

 diameter of base of head ll-12ths of an inch. 



Hah. Marine ; growing in sandy bottom. 



Loc. Port Elizabeth, Natal, Cape of Good Hope. 



Ohs. This specimen, described and illustrated at the request 

 of Dr. J. E. Gray, is in the British Museum. It has been 

 considerably injured, as will presently be mentioned ; and, as 

 the specimen is unique, it has been thought desirable not to 

 extend the injury by sections : hence several parts are doubt- 

 fully described ; but the Tethyadse are so much alike, that 

 what is not present here can, almost with certainty, be sup- 

 plied from the known structure of other and similar species. 



Unless such sponges are carefully removed from their ha- 

 bitat in the sea, soaked in fresh water at once, and as carefully 

 dried, the ends of the delicate asbestiform spicules which pro- 

 ject from their surface are almost sure to be broken off, and 

 the sarcode, if allowed to decompose, to become charged with 

 the mycelium and sporidia of Mucoridese, which are very 

 likely to be mistaken for parts of the sponge : hence I feel 

 now assured that my figure of a trifid spicule bearing a num- 

 ber of globular cells was erroneously supposed to be a part of 

 T. arahica (Annals, 1869, vol. iv. pi. 2. fig. 20). 



The Mucoridese, too, feed upon the soft parts ; and thus 

 the dermal sarcode, as there is no cortex here, especially dis- 

 appears, which, of course, removes at once the pores and the 

 more circumscribed parts of the orifices of the excretory canals 

 or vents, so that the situation and form of both become pro- 

 blematical. This is the case in the present instance ; but T. 

 casula being closely allied in structure and composition to T. 

 arahica^ which I found myself in situ, and have minutely de- 

 scribed and illustrated (Ann. I. c), it is not difficult for me to 

 supply these particulars, as before stated, with almost perfect 

 certainty. 



Indeed, with the exception of the absence of the anchor- 

 head, and the presence of the delicate unequal-armed trifid spi- 

 cule of the sarcode in T. casula, we have every other kind that 

 I have delineated in T. arahica. The surface of the latter is 

 equally silky and asbestiform, from the presence of the pro- 

 jecting ends of the delicate spicules arranged in lines circum- 

 scribing polygonal interstices in which the pores and vents are 

 respectively situated ; and as the outward structure of T. ara- 

 hica so closely corresponds with that of T. casula, we may 

 fairly infer that the internal structure does so also, and there- 

 fore that it is most probably the same as that given in the 

 above description ; without cortex, but with an extremely dense 



