the connection betv/een one of the septal muscles and the peris- 

 tome. The larva is covered by a single layer of epitheliim 

 composed of narrow columnar cells and this is throighout of 

 nearly an even thickness. The supporting membrane, underlying 

 this, is rather thin except in the short stem, 'Nhere it is some- 

 jwhat thicker. The entoderm is about twice as thick as the ec- 

 'toderm, consists of larger columnar cells, apparently somewhat 

 vacuolated, and is everyvhare of about the same character. The 

 stem is apparently entirely filled with the entodenn so as to 

 be without a lumen. About the mouth the ectoderm is a little 

 higher than elsewhere and grades impei^ceptibly into the ento- 

 derm within. Each of the eight short tentacles contains a 

 plug of entodeiTi cells. The entodermal membrane follows the 

 general contour of the whole animal except that that portion 

 of the entiric cavity internal to the periphery of the peris- 

 tome is divided into four very shallow pouches (g. p.) by 

 four folds of the entoderm, the interradial septa. At the 

 peripheral base of a fold the two layers of entoderm are in 

 contact and are continuous with the entoderm of the interradi- 

 al tentacle. More centrally, each fold of entoderm sui-rounds 

 a plate of supporting substance that is continuous with the 

 supporting membrane of both the oral and the aboral surfaces 

 of the larva. Compare Figs. 31, 32, 33 and 34. As has been 



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