246 Description of the Plates. 



case of Taenia caenurus, in tlie brain of the slieep, most usually, 

 though not rarely, in other parts of the body of this ruminant, as 

 also of rodents. (See Description of Preparation 43, p. 136, supra.) 



Figure i. 



Tapeworm, as found in the intestinal canal of man or of a dog, semi-diagrammatic ; 

 after Van Beneden, Mdmoire sur les Vers Intestinaux, Paris, 1858, pi. sxvi., 

 %• 25. 



The asexual ' head' or ' nurse' is armed with a double circlet of 

 spines, as is the case with Taeniae which are harboured in the in- 

 testines of Birds and of carnivorous mammals ; whilst the Taeniae 

 of fish, batraehians, and herbivorous mammals arc not possessed 

 of this armature. Posteriorly to the circlets of spines is seen a 

 circlet of four suckers.- The definition of the segments begins to 

 be evident a short way posteriorly to the head; the segments 

 increase in size and ripeness from before backwards ; the most 

 posterior may be taken to have been such segments as are figured 

 at 3 and 4. The entire compound animal as seen in this figure 

 is trimorphic, consisting of a sexless armed adhesive Miead'' or 

 ' scolex \' of unripe ' proglottides' secondly ; and of ripe proglottides 

 thirdly. 



FiGTJEE 3. 



Half of an unripe segment of Taenia Caenurus, to sliow the generative organs, male 

 and female ; after Leuckart, Die Menschlichen Parasiten, p. 1 79, fig. 2>o. 



a. Water- vascular or excretory system. Two longitudinal vessels, 

 one of w-hich is often much larger than the other, and is 

 not shown in this diagram, run along either side of each 

 segment, parallel with and close to each other, and are 

 connected with their fellows on the opposite side of each 

 segment by a transverse annular anastomosis. This trans- 

 verse connecting vessel takes in the last segment the shape 

 of a median vesicle into which the lateral vesicles converge, 

 and through which they open on to the exterior. In some 

 cases similar openings have been observed in the anterior 

 portions of the Tapeworm, posteriorly to the suckers, and 



