7 6 



W. M. WHEELER. 



mm. in breadth. The dorso-ventral diameter is only 0.5 mm., and is 

 rather uniform both in the center and at the edge of the body. There are 

 no traces of cirri along the somewhat undulating margin. The five pairs 

 of parapodia (fii.) are very small and vestigial. They are neither re- 

 tracted nor do they project above the ventral surface of the body, although 

 they have distinct setae. The lateral organs ("segmental sacs") are very 

 smal 1 , but clearly developed. A ninth unpaired organ could not be de- 



.XXV. 



FIG. A. Myzostoma fisheri sp. nov. Ventral aspect, m., mouth ; ph., pharynx ; 

 g.d., gut diverticulum ; c., cloacal orifice (on dorsal surface); l.o., lateral organ; 

 fin., parapodium ; /., penis; d.e., ductus ejaculatorius ; a.v.d., anterior vas de- 

 ferens ; pv.d., posterior vas deferens ; v.e., vas efferens ; /./., testicular follicles; 

 o.v. , ovaries ; o. , mature ovum. 



tected. The oral orifice is on the ventral surface and rather near the an- 

 terior margin, the cloacal orifice on the dorsal surface a short distance be- 

 hind the center of the body. The pharynx is well developed, the stomach, 

 or succeeding portion of the alimentary tract, is very long and gives off on 

 either side near its posterior end two main gut diverticula. These subdi- 

 vide near their bases and again near their tips (g.d.). All these diverticula 

 are robust, well-developed and extend to very near the margin of the body. 

 The ovary (ov.) is located in the body cavity, to the floor of which it is at- 



