266 SIDNEY F. HARMEB. 



S. neozelanica has formed the subject of several de- 

 scriptions. Hincks (1882) regards the encrusting and Yin- 

 cularian forms as varieties of one species, and shows that the 

 Vinciilarian habit cannot be regarded as a generic character. 

 Waters (1885) states, if I understand him correctly, that in 

 S. magnilabris the bifurcation of a longitudinal row of 

 zocBcia takes place on the distal side of a b zooecium : since 

 the Vincularian S. neozelanica grows in a form in which 

 there is no frequent multiplication of the rows, no b zooecia 

 are found. I do not think that this is an adequate explana- 

 tion of the absence of the b zooecia. It has been shown 

 above that they may be absent or excessively rare in en- 

 crusting species. It is, moreover, not the case that bifur- 

 cation of a row takes place only on the distal side o£ a b 

 zooecium; and these are not necessarily larger than the a 

 zooecia which are their neighbours. Waters in this paper 

 calls attention to the four teeth and the secondary sclerites 

 of the opercnlum of S. neozelanica. In 1887 Waters 

 uses the term "shelf" in describing Steganoporella. 

 Although he refers merely to what I have called the " oral 

 shelf," I have found it convenient to extend the term to the 

 thickened borders of the lateral and pi'oximal walls. The 

 diagrammatic longitudinal section given by Waters (1888) is 

 not quite satisfactory, inasmuch as the epitheca is omitted, 

 and the base of the operculum appears to be continuous with 

 the median process. 



(iii) b Opercula with a A-shaped main sclerite. Oral shelf 

 well-developed, in b zooecia at least. 



This group consists of species in which, for the first time 

 (with the exception of S. connexa in the previous groups), 

 the B zooecia are ordinarily so common that no difficulty is 

 experienced in finding them in even small fragments. Their 

 A-shaped main sclerite gives them a character which is quite 

 distinct from that of the first group of species. The two 

 halves converge distally, and after a longer or shorter parallel 

 con '"se diverge outwards in a curved line, to become continu- 



