168 THE EVOLUTION OF THE METAZOA 



(it is in the Pogonophora and in the entoparasitic Acantho- 

 cephala that the stomodaeum together with the whole 

 digestive system has been lost). Not infrequently the gullet has 

 preserved its ability to protract, or if it had lost this ability, 

 it has been secondarily regained. 



It is therefore not surprising to see that the Anthozoa, too, 

 had inherited their ectodermal gullet from their turbellarian 

 ancestors, and this in the form of a pharynx simplex. Here 

 I should like to call attention to some older observations which 

 previously did not appear so important, but whose importance 

 has been increased due to my interpretation. This is the use 

 of the gullet of anthopolyps as a gripping organ similarly as 

 observed in the Turbellaria. The first of such observations 

 were made, as it seems, by C. Claus (1864) in a pelagic larva 

 belonging to Actiniae (Claus believed that it resembled a cte- 

 nophore). Hertwig considered it to be a larva of Hdwardsia 

 which had a "protrusile stomach tube" ("ein vorstiilpbares Ma- 

 genrohr"). Young Halcampia that are ectoparasites and live as 

 such on medusae behave like Turbellaria and they are even 

 able to adopt their form. Carlgren (1904) reports about the 

 species Halcampogeton papillosus that it can evaginate its "actino- 

 pharynx." The pharynx has an active role also in other Antho- 

 zoa, especially in the adult individuals. According to the broth- 

 ers Hertwig (1879) gullet "fungiert als Magen, da in seinem 

 Inneren die von den Tentakeln ergriffenen und nach dem 

 Munde befordeten Thiere, kleine Mollusken und Crustacean, 

 langere Zeit verweilen und dem Verdauungsprocess unter- 

 worfen werden." 



Cases have been known where the pharynx has been reduced 

 or even lost in Turbellaria in spite of the fact that in these it 

 has been progressively developed. Such a reduction or loss has 

 naturally taken place under the corresponding ecological and 

 biological circumstances. The parasitic Vorticidae show, accord- 

 ing to V. Graff (1882:181) a distinct inclination to reduce their 

 gullet; it has been known that during its adult state the ^2it2i- 

 siticFecampia does not possess a gullet. 



