132 Psyche [August 



known to be, almost without exception, feeders upon decaying 

 animal tissue, and not upon live plant or animal tissue. 



3. We lla^•e repeatedly observed the mites feeding upon old 

 eggshells and dead scale insects. 



4. Individuals of this species confined with fresh eggs of the 

 oyster-shell scale in a small cell, crawled about over the eggs, but 

 finally died, while the eggs remained as perfect and fresh as when 

 first placed in the cell. 



The eggs of Monieziella entomophaga were figured and described 

 by Lignieres. We met with them occasionally at Ames during 

 the summer, finding them beneath empty scales. The egg is white, 

 about one-third as long as the egg of the oyster-shell scale, and 

 similar in shape. 



The Hypopiis Stage. In the case of a great many of the species 

 of the family Tyroglyphidoc, the family to which Monieziella ento- 

 mophaga belongs, there exists a very peculiar stage in the life his- 

 tory, immediately following the first nymphal stage. This stage 

 is known as the hypopns stage, and the individuals then present 

 as hypopi. The hypopus is entirely different from any of the other 

 immature forms of the species and from all other mites. The 

 body is more chitinized, frequently very much smaller; there is 

 no mouth orifice; the legs are ill adapted for locomotion; and as 

 a rule there are many suckers on the posterior ventral part of the 

 body. This stage was primarily an adaptation for the migration 

 of the species, this migration taking place by the hypopi attaching 

 themselves to insects or other Arachnids. However, as was shown 

 by Michael, this stage is vanishing in many species, in some of 

 which the hypopi never emerge from the first nymphal skin, in 

 others the hypopi never become even ixxWy formed. The hypopus 

 finally moults into an octopod nymph, which after a period of 

 feeding, transforms into the adult. 



In France Lignieres discovered the hypopus stage of Monieziella 

 entomophaga, but the present writers have failed to do so in this 

 country, hence we quote from him as follows. 



'"Les liuit exemplaires que je possede actuellment sont le resultat de recherches 

 poursuivies pendant deux annees; durant cclles-ci, j'ai eu la bonne foitime de trou- 

 ver deux fois la Nyviphe hypopiale vivante dans Tinterieur meme de la nymphe- 

 odopode normale; a ce moment, cette derniere etait inerte comme si elle allait effec- 

 tuer une mue ordinaire; mais a I'interieur de son corps, on distinguait ime teinte 

 un peu roussatre denotant la presence de 1' h\-pope." 



