166 Transactions of the South African Philosophical Society. 



tentacles and still in the delicate egg capsule ; others, however, 

 were in some cases observed to have hatched out, and to have 

 reached the stage at which the pre-oral hood and the body formed 

 two approximately equal portions. Some embryos at this stage were 

 observed to exhibit a fairly active opening and closing motion of the 

 two limbs thus forming (pre-oral hood and the body), suggesting 

 that the relatively large development of the hood at this stage may 

 have an important physiological function (respiration ? attachment ? 

 nutrition?). 



The discharge of the ova from the body and lodgment in the 

 brood chamber can readily be observed. Throughout the whole 

 breeding season of about 11 months eggs could be seen in the 

 particular group under observation at any time, in one or other 

 of the specimens, passing up the body cavity singly or in rows of 

 usually about 6 or 8. If a specimen projecting over the edge of the 

 stone (so as to allow of microscopic examination by transmitted 

 light) be examined, the movement of the eggs upwards in the body 

 can readily be observed. At each expansion of the blood vessel 

 from below upwards the eggs or row of eggs was shifted a little 

 further towards the nephridial opening, and on the contraction and 

 emptying of the blood-vessel they were carried back again, though 

 not so far. No evidence of any slow forward movement, such as 

 might be caused by cilia, was apparent. In a typical case the eggs 

 were observed to pass in this manner from the point in the body 

 where it projected from the tube upwards to the nephridial duct in 

 about 10 minutes. Here they became grouped together, remaining 

 thus for 6 minutes. One of the eggs was then seen assuming an 

 elongate slightly bent form (apparently entering the nephridial 

 tube). It was then observed to travel upwards slowly and at a 

 uniform rate inside the nephridial tube which was closely applied 

 to the base of the lophophore. The nephridial tube was then 

 apparently elongated, its opening being covered by the leaf-like part 

 of the lophophoral organ so that on its escape from the opening of 

 the duct the egg was safely carried upwards to the base of the brood 

 pouch and took its place along with the others. It here again 

 assumed a circular form, 0*22 mm. in diameter. Almost immediately 

 after the discharge of the ovum by one nephridial duct the same 

 process took place by the other duct, and so on alternately till all of 

 the group of ova were discharged (in about 15 minutes). 



At the upper end of the mass of developing eggs the larvae were 

 well advanced. In a larva which was observed escaping no trace of 

 tentacles was seen (cf. Longchamps' observations (8)). In one or 

 two cases the larvae were observed swimming about freely, but 





