271 



the American types in being referable to no less than three 

 distinct varieties, two of which may be included in the 

 generic groups instituted for the American species by Dr. 

 Leidy, while the third form is entirely distinct. As 

 species none of the series are precisely identical with any 

 that have hitherto been described and ha-ve consequently to 

 be recorded as new to science. 



The largest and most abundantly developed form to which 

 I will draw attention on this occasion is referable to Dr. 

 Leidy's genus Trichonympha. It is an elongate or pyriform 

 animalcule, having normally a smooth, somewhat inflated 

 posterior region, and an acuminately pointed, highly flexible 

 anterior portion, which is more or less distinctly striated 

 in a longitudinal direction. From Dr. Leidy's species 

 TricJionympha agilis, it differs most distinctly in the relative 

 shortness of the hair-like cilia which clothe the entire sur- 

 face of the body. In the last-named species a portion of these 

 cilia are as long, or longer than the body, and exhibit under 

 certain conditions, a remarkable plume-like aspect. In 

 the Tasmanian species, which, by way of compli- 

 ment to the talented discoverer of the genus, I 

 propose to distinguish by the title of Trichonympha 

 Leidyi, the length of the cilia but little exceeds that 

 of many of the Opalinidae and other previously known en- 

 doparasitic Infusoria. It is furthermore not so easy to re- 

 cognise in the jDresent species that the cilia, M^th respect to 

 their length, form three or four more or less distinct series 

 as obtains in the American variety, for while those that 

 clothe the equatorial region of the body are somewhat the 

 longer, the entire series merge into one another by almost 

 imperceptible gradations. In this respect the species here 

 introduced may be said to resemble an immature stage of 

 the American type. The great flexibility of the anterior por- 

 tion of the body is a feature common to the American and Tas- 

 manian species, both exhibiting in a like manner a tendency 

 to roll this region upon itself in the form of a helix. 



An important point that was left undetermined by Dr. 

 Leidy respecting the structure of Trichonympha relates to the 

 precise position of the oral aperture. The bodies of the 

 animalcules are almost invariably filled with fragments of the 

 woody debris devoured by their hosts the White Ants, which 

 shows that their sustenance is taken into their body in a 

 solid state and is not simply absorbed in the fluid form as 

 occurs with the group of the Opalinidse. A jDrolonged ob- 

 servation of living examples of the American species remitted 

 me by Dr. Leidy, and likewise of the Tasmanian type here in- 

 troduced has resulted in my determining that a distinct oral 

 aperture is developed upon one side of the body at a short 



