POSTLARVAL DEVELOPMENT. 



LARVA. 



Five different colonies of S. radians were collected in Kingston Harbor, 

 Jamaica, on the 6th of Jnly, many of the polyps of which contained free 

 planulse. Although similar colonies had been obtained from this locality 

 on former occasions, and examined with regard to their fertility, this was the 

 first time that larvae were secured. On a second visit a week later two or 

 three other ripe colonies were collected, and others which on being sectionized 

 were found to contain ova. 



On every colony the fertile polyps were in somewhat restricted patches, 

 not all the individuals coming to maturity at the same time. One, two, or 

 three planulae were plainly visible through the nearly transparent tissues of 

 the parent, and were often observed to pass into the tentacles, which thereby 

 became greatly distended, remaining so even when the polyps were retracted. 

 At times the planulae would glide into the lower regions of the polypal cavity, 

 and were then lost to view. While within the parent cavity it was impossible 

 to determine whether the movement of the larvse was, like that of the food 

 particles, dependent upon the ciliary activity of the lining endoderrn or was 

 a result of the larva's own activity. Immediately upon being set free, how- 

 ever, the larvae were able to swim about, the ectoderm being already provided 

 with a layer of cilia. 



The larvae were shot out suddenly, but the actual place of extrusion was 

 not determined, although prolonged observation was made. From their per- 

 sistent entrance into the tentacles it would seem that they made their escape 

 through these organs, and not through the mouth, which was usually closed 

 and depressed. In other instances, e. g., Mamcina areolata and Favia 

 fragum, the sexual products and larvae have been seen to be given out 

 through the oral aperture, the proceeding being accompanied by a peculiar 

 jerking motion of the adult polyp. Von Koch (1897), however, found the 

 larvae of Caryophyllia cyathus to be expelled through the tips of the tentacles, 

 and Lacaze-Duthiers (1873, p. 308) occasionally observed the same in Astroides 

 calycularis. Sections show that the knobbed tip of the tentacles in Sideras- 

 trea is without any permanent terminal aperture. 



Larvae were freely extruded at the time of collection of the corals, and 

 continued to be discharged from time to time for about a month. Under ordi- 

 nary conditions one or two would be set free at intervals, biit upon disturbance 



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