ORDER NOLO TRIG HA . 551 



figures as thus occupied are joined only by their central or oral regions, leaving the 

 two extremities free and often so far separated as to communicate to the conjoint 

 Eooids a contour aptly compared by Miiller with that of a St. Andrew's Cross. It 

 is e\'ident that the former of his two conjectures is the correct one ; the phenomena 

 presented being precisely parallel to those exhibited by two conjugating Paramacia, 

 while in no instance as yet known does the fissive process progress simultaneously 

 from the two opposite extremities leaving the central or oral region last connected. 

 No more fitting example than the present could perhaps be cited in illustration 

 of the advantages that may be derived from a consultation of the too often 

 neglected earlier authorities ; the case in point, moreover, furnishes substantial 

 evidence of the comprehensive knowledge of the Infusoria that was capable of 

 attainment by skilled workers even with the indifferent instruments of the past 

 century. A reproduction of O. F. Miiller's most characteristic outhne illustration of 

 his so-called Vibrio verminus is given at PI. XXVII. Fig. 65A. 



Fam, XII. TRICHONYMPHID-ffi, S. K. 



Animalcules freely motile, but rarely swimming, their movements being 

 confined chiefly to twisting and writhing motions, more or less elongate or 

 vermicular ; cuticular surface entirely ciliate, accompanied apparently, in 

 some instances, by an undulating membrane. Occurring as endoparasites 

 within the intestinal tracts of certain Neuropterous Insecta. 



It seems desirable to comprise provisionally in one small family group the three 

 remarkable infusorial tyjjes, Trichonympha, Pyrsonympha, and Dinenympha, dis- 

 covered by Professor Leidy in the intestinal tract of the American white ant, 

 Termes flavipes. These, while first briefly described by him in the ' Proceedings 

 of the Academy of Natural Sciences of Philadelphia,' for the year 1877, form 

 the subject of a more extensive communication, with accompanying illustrations, to 

 the same journal, published in March 18S1.* All three animalcules were found 

 by Professor Leidy associated together under the following circumstances. Seeking 

 for microscopic animals beneath stones and fragments of wood in the American forests, 

 his attention was attracted to the white ants in question, their intestines, as seen 

 through their translucent abdomens, being considerably distended with a brown sub- 

 stance. Feeling curious to ascertain the nature of this matter, it was examined 

 and found to consist largely of the three infusorial parasites here described, mingled 

 with minute particles of decayed wood, an abundance of Spirillum and the fila- 

 ments of an algal referable apparently to the genus Arthromitus. In many 

 instances, however, the Infusoria were present in such prodigious quantities as to 

 make up the greater portion of the bulk of the intestinal pulp. 



The decision previously arrived at by the author to provisionally retain these three 

 genera in the single family group of the Trichonymphida; is in no way affected by 

 the more recent accounts and illustrations of the several species now to hand, and 

 is indeed fortified by the following extract from Professor Leidy's latest description : 

 " Of the parasites of our termite there appear to be three or four, or perhaps more, 

 distinct species of remarkable protozoans, but of this I am not positive, for I have 

 suspected that several, which I at first viewed as such, may be only different stages 

 of the same. On the other hand, certain forms which I have regarded as younger 

 stages of the species as I have distinguished them, may on future investigation prove 

 to be equally distinct." Or again, " In the following descriptions I have of course 

 attempted to represent them as they have appeared to me from time to time, but I 



* Through the receipt of a separate copy of this communication, immediately on publication, the 

 author is especially indebted to Professor Leidy for the opportunity of reproducing in this treatise 

 his exquisite drawings and latest data elicited concerning the structure and habits of these remarkable 

 organisms. 



