V 



14 ILLINOIS BIOLOGICAL MONOGRAPHS [14- 



with fine meshes. Musculature weak. Habitat: In aquatic snakes, Cro- 

 talinae, Colubridae, Elapinae and Amphibia. 



Tyj>e species : Ophiotaenia perspicua La Rue 1911. 



In the descriptive section the greater number of species of the 

 above named genera have been described, with exception of species of 

 Acanthotaenia and Corallobothrium. It has been impossible to write up 

 the descriptions of certain species inquirendae of which no material 

 could be obtained, and for which only very meager descriptions have 

 ever been written. It is hoped that these may be properly considered 

 at a later time. 



METHODS OF TECHNIQUE 



The following methods have been used by the writer in the work 

 on this group of cestodes. To a large extent they may be used with 

 success on all groups of cestodes although it should be understood that 

 certain methods which give admirable results with the relatively small 

 and thin cestodes here dealt with will not give equally good results if 

 used on the large forms such as Taenia. 



The larger forms were picked out of the intestinal contents, care 

 being taken to free the head if the worm was attached to the mucosa. 

 These were then repeatedly dipped in the killing solution until the worm 

 ceased to contract. The worm was allowed to lie for 15 minutes to 2 

 hours in the same fluid. Metallic instruments are to be avoided if cor- 

 rosive sublimate solutions are used for fixation. When the smaller 

 worms were encountered the whole intestine slit open was placed in a 

 small quantity of physiological saline solution in a bottle which was then 

 shaken vigorously for about 3 minutes, the killing fluid was added and 

 the whole then shaken for one half minute. This is according to the 

 method of Looss. The fixative was permitted to act 3 to 10 hours. 



The killing fluids used were hot 5% solution of formaldehyde, and 

 hot or cold saturated aqueous solution of corrosive sublimate to which 

 was added glacial acetic acid to make 1 to 2%. Some other fluids were 

 tried but nothing gave better results for the purposes of this study than 

 the corrosive acetic mixture used hot or cold. For most of the worms 

 the cold solution was preferable to the hot which sometimes gave rise to 

 artifacts if used at too high a temperature. In no cases were the worms 

 stupefied before killing. 



The usual methods were used for hardening and dehydrating. Speci- 

 mens were usually preserved in 85% alcohol after running up through. 



