28 6 



SIDNEY F. HARMKR. 



the main sclei'ifce; their teeth number 16 to 21, the proximal 

 ones being very minute. The a opercula (which, like the 

 others, are thin and delicate) have even more vestigial teeth ; 

 the more distal ones alone can be made out, and not more 

 than twenty can be counted. The opening of the tube is 

 unusually wide, its sides sloping very much outwards and 

 downwards, and then somewhat approaching one another, to 

 join the basal wall, which completes the tnbe. In a good 

 many of the zooecia one of the lateral walls of the cavity of 

 the median process is not developed. The cryptocyst may 

 be thickened at the commencement of its descent. 



Specimen g (Tizard Reef) agrees well with many of the 

 other specimens. Its back is very nodular, probably from 

 having encrusted an irregular surface. The opercula are 

 normal, a having twenty-seven small teeth, and b twenty-four 

 teeth (one operculum of each kind mounted) ; b is short and 

 nearly semicircular. 



Specimen h is the merest fragment, but the characters of 

 its (dry) opercula show it to belong to this species. It is of 

 importance as giving another locality for the species. 



Measurements of Opercula (in fx) and Number of 

 their Teeth. 



A B 



' The lengtli is measured obliquely from the jiroximal end of one of the 



halves of the main sclerite to the distal border (median) of tiie operculum. 



■^ Leavinjf one operculum out of accouul, the figures would be: — b, 

 diam. 430-570; length 590-720. 



=* One or iwo bnialier 0|>ercuia (Bj were iiol measured. 



