214 Charles Lincoln Edwards 



the slime and the living organisms which have been allowed to 

 remain on the bottom of the dish and form a culture for food when 

 the stale water has been decanted at each period. As the young 

 animal feeds, the mid-enteron enlarges into the prominent larval 

 stomach, occupying the middle third of the coelom. By the ninth day 

 the divisions of the enteric canal are clearly sho"wn. The first or 

 dorsal loop is suspended by its mesentery from the mid-dorsal in- 

 terradius. It includes the cesophagus and stomach, and terminates 

 ventrad of the anus. From the posterior end of the stomach the in- 

 testine turns down in the left ventral interradius, and runs forward 

 as the second or left loop. This portion gradually goes over to the 

 right ventral interradius, until just in front of the stomach, where 

 it turns again posteriorly, and as the third, or right loop, goes in 

 the right ventral interradius to the posterior end of the stomach. 

 Here the intestine makes a sharp bend dorsad along the right side 

 of the stomach, and terminates in the anus, which is now near the 

 posterior end of the mid-dorsal region of the body. The large larval 

 stomach thus crowds the second loop ventrad alongside of the third 

 loop, and, at the same time, the large Polian vesicle lying in the left 

 half of the coelom, pushes the first loop of the enteron to the right. 

 This position is maintained together with the relatively large size 

 of the stomach, in a general way, during the developmental stages 

 of my series, but following about the fortieth day the second loop 

 comes gradually dorsad toward its adult position. 



The stone-canal has a peripheral expansion, the madreporic vesicle, 

 similar to that described in Cucumaria planci by Ludwig, 1891. In 

 Holothuria floridana the stone-canal is found in the embryo of four 

 days. Later it lies in the dorsal mesentery and the madreporic 

 vesicle is at the surface in the mid-dorsal line of the median plane. 

 The outer wall of the vesicle at first is continuous with the surface 

 of the body-wall, but later the vesicle lies deeper in toward the 

 coelom. In Cucumaria planci, Ludwig says that the dorsal pore is 

 obliterated in eighteen to twenty days, and that the madreporic 

 vesicle opens into the coelom on the ninety-eighth day. In Holothuria 

 floridana, in the sixth day, the dorsal pore is not open at the surface, 

 and in my oldest stage, eighty-seven days, the madreporite is still 

 continuous with the tissues of the body-wall. 



