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tracted. Snout small, rounded or emarglnate in front, flattened con- 

 siderably (p1. XVI, figs. I, 2), but may be almost completely withdrawn 

 into the swollen succeeding portions of head, as shown in fig. 3. 

 Oblique cephalic furrows lie on the ventro-lateral margins. As seen 

 from in front when strongly contracted, the snout presents an elliptical 

 outline, separated by a deep groove from the tissues of the succeeding 

 regions, which have been moved forward to surround the retracted head 

 (p1. XVI, fig. 3). This groove passes through the cephalic furrows, 

 and is continuous with them. The anterior portion of the esophageal 

 region also is deeply wrinkled with circular grooves. Proboscis pore 

 subterminal ; proboscis rather small, whitish in color. Mouth ex- 

 tremely variable in size, according to state of contraction of anterior 

 portions of body. When head is well extended the mouth is situated 

 well back from snout and represents a large, much elongated opening 

 (p1. XVI, fig. 2), but when head is strongly contracted the mouth as- 

 sumes the proportions of a small, rounded pore (pi. xvi, fig. 3) on the 

 ventral surface a little posterior to the retracted snout. 



Esophageal region is often greatly swollen just behind the widely 

 opened mouth when body is well extended, very much as in Cere- 

 hratulus. There are many indications that in this species of Tcenio- 

 soma the esophagus is often filled with water, which is ejected at inter- 

 vals, and thus serves to some extent as a respiratory organ, as has often 

 been considered the case in Cerebratulus . The greater portion of 

 esophageal region is subcylindrical, becoming more flattened pos- 

 teriorly. 



Intestinal region often very flat and ribbon-like (p1. xvi, fig. i), 

 usually much wrinkled and showing a tendency to roll up into an ir- 

 regular spiral, as has been noted in other species. This region may 

 contract to but a small fraction of its usual length, becoming at the 

 same time nearly as thick as broad. Posterior extremity not very 

 slender. 



Color. — General color of body usually deep brownish red, or dark 

 red with only a tinge of brown ; sometimes of a deep mahogany color. 

 The body color often appears as if covered with a delicate whitish 

 bloom. Anterior portion of head is much deeper brown or almost 

 black, sharply marked off from a narrow white border which occupies 

 the terminal and lateral margins of snout. The dark brown or blackish 

 color is limited to the dorsal surface of snout, and usually consists of a 

 rather narrow transverse marking which shades off gradually into the 

 general body color posteriorly. It is bordered laterally by the white 

 margin mentioned. 



