472 Gcoffrey Smith 



all her intevnal ovgaus except the nerve cord and a few shreds of 

 ventral ectoderm. There is no brood-pouch ; this is showu in the 

 transverse seetion fig. 10, where the embryos are seeu hing in the 

 body cavity of the mother, all the maternal tissues having degenerated 

 except the nerve cord. The emi)rvos are set free by the cuticle 

 Splitting at the points corresponding to the thoracic segmeuts; and 

 after parturition the female appears as a mere cracked shell of its 

 former seif; nor can it take any further part in reproduction though 

 it may continue a feeble existence for a few days or cven weeks. 



2. Life-history. 



The youug are set free from the body cavity of the mother at 

 a stage which may be called the normal segmented larva (fig. 11). 

 This larva is fully segmented; its body is dotted over with yellow 

 In'anching pigment cells, and its mouth-parts are essentially the same 

 as those figured for the later Praniza larva (fig. 2). In its thorax 

 are two greenish bodies, diverticiihi of the gut, which coutain the 

 remains of the embryonic food yo!k. These larvae can remain jdive 

 in this state without taking in food or growing, for a remarkably 

 long time (7 or 8 weeks); for their further developemeut however it 

 is necessary that they should become attached to fish and when this 

 is accomplished the next larvai form, the Praniza, is rapidly assumed; 

 this is proved by the oeeurrence of small Pranizae not exceeding tlie 

 average size of the normal segmented larvae (0,S— 1,2 mm). 



The characteristic form of the Praniza is shoAvn in fig. 1. It 

 lives loosely attached to the fish on which it feeds; after a period of 

 unknown duration it drops off and undergoes the final metamorphosis 

 lipon the sea-bottom, whence it can l)e collected in fair abundance 

 at Kaples, together witli adults of both sexes, especially among the 

 roots of the Aveed Fosidonid ('(iroìiiiii in 5 — 3(t meters. 



Now besides the small normal segmented larvae measuriug about 

 1 niillimeter and the non-segmented Pranizae whicli vary in size from 

 1 — 8 mm, another form of larva occurs wliich may be called the 

 giant segmented larva (fig. 12). All except a few specimens of 

 this form measured about 4 mm ' ; they show no trace of sexual Cle- 

 ments; their e-ut is not infiated and thev dilfer from Pranizae in 



' Of 29 such larvae 20 lueasured l)etween 3,75 and 5.5 mui. and ■> measured 

 2— :{ mm. the measurements being symmetrieall}' grou]ied round 4 mm. 



.J 



