﻿Plate 32 

 Dendrostomum zostericolum Chamberlin 



1, Dissection of a specimen from Ensenada, Baja California; X 2. In this 



example the postesophageal gut (0') is unusually long and does not start to 

 coil around the ascending spiral at +, the usual place. The contractile 

 vessel has 12 Polian tubules. Length of specimen 190 mm. 



2, Detail of intestinal coecum and spindle muscle, showing mode of attachment 



of the latter to intestinal wall posterior to coecum. 



3, View of the inside of base of left nephridium with nephridiopore in center and 



inner opening of nephrostome at upper left; X 10, 



4, Nuchal organ; margin of oral disk above and a branch of a dorsal tentacle on 



right. 4, a. Brain X 10. CO, circumesophageal commissure; /, nerves to 



tentacles ; 

 C, coecum; CG, ciliated groove; CV, dorsal contractile vessel; F^-F^, fixing 

 muscles; M, mesentery of esophagus; A^, nephridium; A'^', nephrostome; O', 

 postesophageal intestine; PT, Polian tubules; S, spindle muscle; W, wing 

 muscles of rectum. 



Plate 33 

 Dendrostomum perimeces Fisher 



1, Dissection of paratype; X 1. Note the very long intestinal spiral, few Polian 



tubules, relatively short nephridia; absence of fixing muscles (intestinal 

 anchors). Oblique muscle bands of body wall are indicated. 



2, Another specimen showing esophagus, contractile vessel, rectum, and top of 



intestinal spiral; X 2. 



3, Enlargement of posterior end of contractile vessel of figure 1. 



A, anus; CV, contractile vessel; A', nephridium; 0, esophagus, O', postesophageal 

 intestine; PT, Polian tubules; S, spindle muscle; W, wing muscles. 



Plate 34 

 Dendrostomum dyscritum, new species 



1, Dissection of a specimen from Monterey Bay (see pi. 30, fig. 3); details of 



Polian tubules omitted. F^-F^, fixing muscles (see also figure 87) ; G, gonad. 



2, Skin gland from posterior third of body; X 200. 



3, Contracted specimen from near Point Conception; X 1. 



4, One of the paratypes, Monterey Bay; X 1. 



5, Detail of end of the intestinal spiral. 



Plate 35 

 Dendrostomum. lissnm, new species 



1, Type; X 4. The Polian tubules have been omitted for simplification and 



only upper coils of intestinal spiral are indicated. 



2, Type; X 3. The dorsal branch of each dorsal tentacle has been removed to 



show the heart-shaped nuchal organ. 



3, Two of the glands from body just anterior to the posterior dark area; X 200. 



4, Oral disk and bases of the four or eight tentacles; X 0. The arrows indicate 



the primary radii. 

 A, anus; F^-F^, fixing muscles; G, gonad; A'", nephridium; A^^', nephridiopore; NO, 

 nuchal organ. 

 448 



