STERELMINTHA. 93 



ccptible, which are either merely provisions for fixing the mouth 

 firmly when in the act of imbibing food, or else they may act as 

 lancets, by scarifying the surface from which nourishment is de- 

 rived. From the outer orifice we may trace a canal which extends a 

 little way into the body, and becomes slightly dilated ; into the 

 bottom of this cavity a small tongue-shaped organ (d) is seen to 

 project, having its surface perforated by a number of exceed- 

 ingly minute holes, which indeed might be looked upon as the 

 real mouths destined to imbibe the nutritious juices, and convey 

 them to the stomach. The stomach, (c, c, c, c, c,) which has 

 been partly removed on the right side of the figure, is a wide 

 canal, extending through the whole length of both divisions of 

 the body, and passing by a capacious cross-branch from one half 

 to the other, so that the nutriment taken in by either mouth will 

 pass freely to the opposite side. From these central channels 

 great numbers of blind canals issue, resembling those of Distoma 

 and Planaria, which ramify extensively; there is, however, no 

 anal orifice or outlet for excrementitious matter. 



(123.) But, besides the ramifications of the alimentary canal, 

 other vessels are discernible, running through the parenchyma of 

 the Diplozoon, where nutritious fluids circulate, and which corre- 

 spond to the vascular arrangement met with in Planaria. Of 

 these the main trunks only are represented in the figure; the 

 branches given off from them, which are very numerous, being for 

 the sake of distinctness entirely omitted. Each half of the body 

 contains four of these vessels, (/, /,) which run from one extremity 

 to the other. In these a fluid is observed to move, running in 

 the directions indicated by the course of the arrows in the diagram ; 

 namely, in two of them from the head toward the posterior end of 

 the body, and in the other two in an opposite direction. This ru- 

 dimentary circulation must be for the purpose of more perfectly 

 diffusing through the system the fluids which result from the 

 process of digestion, and which are probably taken up by imme- 

 diate osculation, between the terminations of the branches from 

 the stomach, and the origins of the vascular system. 



Upon the opposite side of the figure is given a diagram of 

 the arrangement of the generative apparatus insulated from sur- 

 rounding parts, so as to give the reader a distinct view of the 

 different organs composing it. 



(124.) As in the two last described species, we find both oviger- 

 ous and impregnating organs constituting complete hermaphrodism, 



