VI. The Complete Scyphistoma . 

 With the increase in size of the scyphistoma the calyx is 

 relatively more expanded and more tentacles are formed. Scyph- 

 istomas that are still quite small are found with twenty-four 

 tentacles, and the full number of tentacles, thirty-two, is 



acquired long before the scyphistoma had attained its maxi- 

 n am size. The tentacles appear, when they are arranged sym- 

 metrically, in cycles of eight ; but the larva is as variable 

 as is the adult, and the final number of tentacles, while never 

 less than thirty-two, very often exceeds that number. 



The interval between the acquisition of tlie full number 

 of tentacles and the beginning of tiie next stage seems to be a 

 long one. The great majority of scyjjhistomas were found in 

 this stage, and it is during this time that the buds are given 

 off. The four angles of the mouth are now very pronounced, 

 and in the proboscis there are four deep longitudinal grooves 

 corresponding with them. Fig. 46. Between the angles of 

 the proboscis there are, in preserved specimens, four marked 

 depressions in the peristome. These are shown in Figs. 46 

 and 47. The septal muscles do not arise from the bottom of 

 these depressions but from high up on the outer sides, (Figs. 

 46 and 47.) It seems hardly possible that these depressions 



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