OF THE CYSTIC ENTOZOA. 89 



Cysticercus, with the exception of its being entirely buried in the 

 body of the animal, consequently also it is neither furnished with 

 teeth nor suckers. There is no separate absorbent apparatus in 

 the sac of the animal, and this part of its body appears to be com- 

 posed of one membrane only, which is analogous to the external 

 membrane of the sac of Acephalocystis. The cyst of this animal 

 at first appears to be composed of three membranes, but a little 

 examination proves the outermost to consist of peritoneum only, 

 the two others being similar to the analogous membranes of the 

 cyst of Cysticercus rattus, namely, an external for defence, and 

 an internal for absorption of nourishment. 



This animal was found attached to the intestines of the Balearic 

 Crested Crane (Balearicapavonia, Vigors) beneath the peritoneum. 



V. OF CJSXURUS. 



The next animal we have to describe is Csenurus. It is in the 

 species belonging to this genus that the first vestiges of extremi- 

 ties are perceived, to which form of structure w r e are led through 

 Diskostoma the discs described in the latter being without doubt 

 analogous to the pedicles of the Caenurus. 



Ccvnurus cerebralis, an animal frequently found in the brain of 

 the sheep and other ruminants, has been long known to natural- 

 ists. This animal is composed of a double sac, from the external 

 surface of which proceed a number of small bodies, termed pe- 

 dicles. These pedicles are contained between the two membranes 

 of the sac, project at right angles from its surface, and are armed 

 at the extremity with a double circle of teeth. 



The sac of the Csenurus is composed of two membranes, the 

 outermost of which acts as an organ of defence, the internal, 

 containing a layer of absorbent cells, acts along with the larger 

 cells contained in the pedicles as organs of nutrition. The natu- 

 ral size of the pedicles is about the one-eighth of an inch in 

 length. It is divided into two parts, the basal and distal. The 

 former contains the absorbing cells already spoken of, which, 



* Transactions of the Royal Society, Edinburgh, Vol. xv. p. 564. 



