I So Papers from the Jllarine Biological Laboratory at Tortugas. 



mm. wide, while the largest is 4.3 mm. long and 2 mm. wide. These measure- 

 ments were made on material which had been preserved in alcohol for a year. 

 In all of my specimens of Zoanthina the mouth and pharynx are fully 

 formed and the size of the septa and absence of the endodermal thickenings 

 between the septa indicate that these larvse are more advanced in develop- 



FlG. I. Entire specimen of Zoanthina, viewed from oral pole; specimen stained and 

 mounted in balsam. Ectoderm shaded by radial lines, mesogloea by oblique lines, and 

 endoderm by light stippling; ciliated groove deeply stippled. 



ment than those of Zoanthclla which I have studied. The mouth-opening is 

 round in outline, but the pharynx is compressed laterally, as shown in text- 

 figure I. In this genus the pharynx extends inward at least as far as the 

 circular constriction, about one-third the length of the entire body (plate i, 

 fig. 2a). The walls of the pharynx are thrown into longitudinal plications, 

 which become continuous with the mesenterial filaments of the macrosepta 

 (plate 4), as in Zoaiithella. 



The septa are relatively larger than in Zoanthella, and this is especially 

 true of the microsepta. but Van Beneden holds that their arrangement and 

 order of appearance are the same in the two genera, ;. c, the dorsal direct- 



