34 ARTHUR DENDY. 



occur only on the concave surfaces of the lamellae (pi. xviii, 

 fig. 4), while the oscula are all on the convex surfaces. 



" By far the most remarkable instance of this kind is, how- 

 ever, afforded by a boring Suberite which we have described 

 under the name Cliona dissimilis (p. 227, pi. xxv, fig. 5, 

 &c.). Here the sponge has bored its way into a flattened 

 coral which it completely surrounds ; hence it has itself acquired 

 a flattened, lamellar form, and we find the pores collected in 

 areas (woodcut, fig. 11, pa.) on one side of the sponge, and the 

 oscula (woodcut, fig. 11, o.) on the other." 



'' There is no other known example, so far as we are aware, 

 of a lamellar Suberitid sponge ; and even the species in question 

 is lamellar only because it has bored into a lamellar coral, and 

 yet the pores and oscula are arranged just as they would be in 

 a free-living frondose sponge, such as P h a k e 1 1 i a. There must 

 be some strong reason why as soon as a sponge, for any cause, 

 acquires a lamellar form, the oscula become confined to one 

 surface and the pores to the other, and to account for the occur- 

 rence of this condition in genera so widely separated as 

 Gellius, Myxilla, Phakellia, and Cliona. What this 

 reason may be we cannot at present say." 



I am still no better able to give an explanation of this 

 curious phenomenon than I was when the above passage was 

 written ; but the facts appear to me to be conclusive evidence 

 against the value of the peculiar arrangement of the pores and 

 oscula as a family character. 



But even if it were allowed that the arrangement of the 

 pores and oscula were a character of family importance we 

 could not put Eilhardia and Teichonella in the same 

 family, for, as I have shown, they differ widely from one 

 another in this respect. Then, according to Polejaeff's dia- 

 gnosis, not Eilhardia, but Teichonella, would have to 

 come out of the family Teichonidse. As a matter of fact the 

 family ought to be abandoned altogether, and the three species 

 which have been at various times placed in it distributed as 

 follows : 



