A REVISION OF THE GENUS STEGANOPORELLA. 295 



wide distribution, but that Steganoporella itself is pri- 

 marily a southern genus. 



It is noteworthy that the species of Siphonoporella at 

 present known (see p. 231) are both Australian; while this 

 region has a good representation of the allied genera Tha- 

 lamoporella, Thairopora^ and Diploporella. It is not 

 improbable that Australia may have been a centre from 

 which species of this group have spread. All the species of 

 my third group (with A-shaped main sclerite in the b oper- 

 cula) occur in Australia, although S. magnilabris occurs all 

 round the world. Of the second group (with four teeth on 

 the main sclerite of the a opercula) S. neozelanica occurs 

 in New Zealand and Tongatabu, and S. auriculata in 

 Madagascar. Of the first group (with n -shaped main 

 sclerite in the b opercula), S. tubulosa, S. lateralis, and 

 possibly S. sulcata are Australian ; the first being restricted 

 to Australia (so far as is at present known), the second 

 occurring as a Tertiary fossil in Victoria, found recent in 

 Torres Straits and extending to Tahiti ; and the third found 

 also in the Indian Ocean. The other two species are known 

 from isolated localities, — S. simplex from the Amirante 

 Islands, in the Indian Ocean, and S. connexa from Brazil. 



EXPLANATION OF PLATES 12 & 13, 



Illustrating Mr. Sidney F. Harmer's paper " A Revision of 

 the Genus Steganoporella." 



PLATE 12. 



The figures on this plate were all drawn to the same scale (camera lucida, 

 Zeiss A obj. ; afterwards x |), and are X 40. (B. M. = British Museum ; 

 C. M, = Cambridge Museum.) 



Fig. 1. — Stegauoporella lateralis, MacGill (p. 242), Zooecium a. 

 Tahiti, Manchester Museum, 



VOL. 43, PART 2. NEW SERIES. X 



