1908. 1 Records of the Indian Museum. 17 



colour in living polypides and in specimens preserved in spirit. In 

 specimens which have been cleared with cedar-wood or clove oil and 

 mounted in Canada balsam, however, the whole shield practically 

 disappears, unless some method of double staining is employed. 



Mimentary Canal — 



When the tentacles are unfolded the circle of the lophophore 

 surrounds a relatively large vestibule, the floor of which is often 

 rather deeply concave, its exact form depending on the state of 

 the alimentary canal. It is covered with long cilia which waive 

 towards the mouth, a large circular aperture situated at the lower 

 end of the vestibule. The mouth leads into a funnel-.shaped oesopha- 

 gus, which opens in its turn into the stomach, to which it is at right 

 angles ; the opening is almost exactly in the middle of the anterior 

 (" oral ") surface of the stomach. There is no epistome. The 

 colon, a wide tube which can be entirely shut off from the stomach 

 by a constriction, starts from one side of the latter but bends round 

 behind it in such a way that the rectum, which is separated from 

 the colon by a distinct constriction, comes to lie parallel to the 

 cesophagus. The rectum is capable of great contraction and 

 often takes on a spherical outline. In this condition it does not 



--:\\>^\^^ 



Fig. 6. — L. colonialis, polypide with retracted lophophore, from in front. - 



reach the floor of the vestibifle but lies at the ]>ase of a narrow pit 

 devoid of cilia. When the rectum is extended, however, the anus 

 opens on the floor of the vestibule a short distance from its 

 upper limits. Of all the divisions of the alimentary canal the 

 stomach is by far the most bulky, filling up the greater part of the 

 space in the calyx. Its anterior and posterior walls consist of 

 greatly elongated cells ; its base is fastened to the base of the 

 calyx by means of a strand of tissue apparently resembling a dice- 

 box in shape but very difficult to distinguish clearly as it takes all 

 the stains I have tried on it feebly. The only part of the animal 

 (except the shield) that is not absolutely colourless, is the stomach, 

 which has a faint yellowish tinge, 



