﻿Plate 28 



1, Dendrostomum perimeces Fisher; Head of a specimen drawn from life, X 5, 



showing tentacles in natural feeding position, the smooth brown collar, the 

 whitish sphincter zone, and behind this the anterior part of papillae zone. 



2, Dendrostomum pyroides Chamberlin, X 5; View looking down upon mouth, 



showing base of the four groups of tentacles, the grooves leading to mouth, 

 and the serrate border of grooves. Between the two dorsal tentacles is the 

 nuchal organ, A^'. Preserved specimen. 



Plate 29 

 Dendrostomum pyroides Chamberlin 



1, Dissection viewed from above; X 2. The contractile vessel and Polian 



tubules are shown in solid black, but not all of the tubules are indicated. 



2, Oral disk and bases of four groups of tentacles (1-1 V) ; X 12. Specimen from 



Boca de la Playa, near Ensenada, Baja California. 



3, Side view of esophagus greatly enlarged to show network of vessels arising 



from the contractile vessel (CV) and enveloping esophagus. At lower end 

 of figure the origin of the Polian tubules of left side only is shown. 

 CV, contractile blood vessel; F^-F^ fixing muscles of gut; G, gonad; NO, nuchal 

 organ; 0, esophagus; R, left retractor. 



446 



