72 



Fig. 

 Fig. 



10. Ældre stadium. 



11. Stadium, der i alt væsentligt modsvarer den ud- 

 vijjlede knops organisation. 



Pl. II. 



Embryonaludviklingen af Distaplia magnilarva. 



Fig. 1 og 2 af Heider (23) efter r. Daridoff (12) visende 

 medullaiTørets og canalis neurentericus dannelse. 



Fig. 

 Fig. 



10. 

 11. 



Fig. 



3. Ung larve, ikke væsentlig ældre end det i fig. 2 

 afbildede stadium. Visende medullarrorets første 

 begyndelse til differentiering, samt jjeribranchial- 

 sækkens dannelse. 

 Fig. 4. Samme stadium i tversnit. Viser det ene peri- 

 branchialsækanlægs forbindelse med ektodermen. 



Fig. 5. Ældre stadium seet fra dorsalsiden. De 2 an- 

 læg til peribranchialsækken sammenvoksede og 

 gjællespalterne dannede. Medullarroret fortil 

 sammenvokset med gjælletarmen. 



6. Samme stadium seet fra venstre side. 



7. Repræsenterer den voksne larve. Viser larve- 

 hjernens udvikling og forhold til den senere liypo- 

 physis, flimmergrube og ganglion. Tidligere af- 

 bildet (31), pl. 39, fig. 33. 



8. Ungt individ med det fastsiddende dyrs bygning. 

 Larvehjernen lindes ikke. Gangliet er helt af- 

 snoret. Hypophysen viser .sig som en enkel 

 kort cylinder. 



Fig. 9. Voksen larve, visende dennes bygning i alminde- 

 lighed. 



Fig. 

 Fig. 



Fis 



Later 



Stage corresponding in all essential points to 



the organisation of the developed bud. 



stage, 

 corresponding in 



Plate XII. 

 Embryonic development of Distaplia magnilarva. 



Figs. 1 and 2. From He/der (23) after v. Davidoff (12); 



showing the formation of the meduUary tube 



and the neurenteric canal. 

 Fig. 3. Young larva, not much older than that in fig. 2, 



showing the commencement of differentiation in 



the medullary tulie, and the formation of the 



peribranchial cavity. 



4. Same stage in transverse section, showing the 

 connection of one rudiment of the peribranchial 

 cavity with the ectoderm. 



5. Dorsal view of later stage. The 2 rudiments 

 of the peribranchial cavity coalesced, and the 

 branchial stigmata formed. The medullary tube 

 coalesced in front with the branchial gut. 



6. Left view of same stage. 



7. Full-grown larva. Shows development of larval 

 brain, and its relation to the subsequent hypo- 

 physis, dorsal tubercle and ganglion. Previously 

 given 31, Pl. 39, fig. 33. 



8. Young animal with the structure of the attached 

 animal. Larval brain not to l)e found. Gang- 

 lion completely constricted. Hypophysis appears 

 as a single short cylinder. 



9. Full-grown larva, showing general structure. 



Fig. 



Fig. 



Fig. 



Fig. 



Fig. 



Fig. 



