278 SIDNEY F. HARMER. 



usually continued across the proximal edge of the deep lateral 

 recesses to join the sides of the zooecia, and the lateral re- 

 cesses may be margined in their proximal half by a thin 

 upstanding flange of calcareous matter. The lateral walls of 

 the tube are well developed. In both a and b the base of 

 the tube may, in some cases, be a hole in the descending 

 cryptocyst, a narrow portion of which intervenes between it 

 and the distal wall. The walls of the tube may not, how- 

 ever, grow from the entire margin of this hole, the tube 

 growing upwards in such a way that its lateral walls unite 

 with the distal wall of the zooecinm, and being thus incom- 

 plete above. The appearance seen in the a zooecinm of fig. 9 

 is thus produced. The basal wall of the zooecinm is, of 

 course, invisible from above. 



The epithecal sclerites are long and gentl}- curved, reaching 

 the base of the opei'culum, nsually more distant from one 

 another in A than in B. The B opercnla (fig. 36) are re- 

 markably strong, with coarse, sharply pointed, nearly erect 

 teeth, which are so strong that their bases can be clearly 

 seen from above through the dry operculum. The longest 

 teeth may reach 65 ^ in length. The submarginal sclerite 

 is strong. The halves of the main sclerite are widely 

 separated distally, enclosing a space which is dilated dis- 

 tally, the edge of its chitinous floor forming a somewhat 

 pointed arch with the proximal part of the main sclerite. 

 The two bars composing this end proximally in a stout pro- 

 jection. The occlusor tubercle is very large and strong. 

 The basal (1)) and oblique (o) sclerites are as usual well deve- 

 loped. The characteristic form of the a opercnla (fig. 37) 

 has already been described ; their most striking characters 

 are their large size and the development of a strong tooth 

 just beyond the occlusor tubercle on each side of the main 

 sclerite, which is far removed from the periphery of the 

 operculum. The occurrence of a distinct and strong basal 

 sclerite is an unusual feature in a opercnla. Should an 

 A zooecinm give rise to two younger zooecia at its distal end, 

 its oral arch and its operculum are more or less semicircular. 



