ON AN ACARUS ASSOCIATED WITH BANANA. 107 
named Detriticole (frequenters of rubbish).* They are of such 
small dimensions as scarcely to be visible to the naked eye, or 
not at all when placed upon a white ground. When fully grown 
this acarus is of a very taint pink colour, and its somewhat broadly 
elliptical body is terminated in front by a conical snout. ‘This latter 
is composed of a central portion with two three-jointed “feelers” 
applied to it on either side. Outside these feelers are large 
mandibles, the toothed shear-like extremities as well as the swollen 
bases of which are very conspicuous objects. ‘lhe nature of the 
attachment of these organs is such as to endow them also with 
considerable movability, and their structure renders them also 
very effectual organs in procuring food. These mites, too, have 
four pair of five-jointed legs, each terminated by a single stout 
strongly-hooked claw. The legs all bear stout bristles of various 
form, and the first and second pair have on the upper surface of 
their terminal joints a single club-like body of even breadth. In 
addition to the limbs the body bears also a few stout and relatively 
long bristles, and its two chief outlets are guarded by curious 
suckers, the two on each side of the genitalia being raised on 
nipple-like protuberances, whilst the single haustellum, on either 
side of the cloacal aperture, is not raised, but carries, in the male 
sex especially, a sub-triangular appendage. 
‘This little mite belongs to the genus Rhizoglyphus (root gauger) 
of Claparéde, as restricted by Murray, a genus which contains at 
least two species, both of which have been described and figured, 
amongst others, by the former of these authorities. 
Concerning the habits of acari belonging to this genus, it may 
be sufficient to remark that Claparede procured numerous examples 
of both the species alluded to, in the neighbourhood of Geneva, 
Switzerland, where they occurred in the tubers of potatoes and 
dahlias and in the half-decayed stems of cabbages, situations in 
which they were met with in great quantity. Reference to his 
descriptions and figures in the “Zeitschrift fur Wissenschaftliche 
Zoologie” for 1868 shows that the banana mite is not the first of 
these two species, his Hypopus Dujardinii (Rhizoglyphus echinopus, 
Fum. et Rob.), and though it certainly much resembles the second 
species— his Rhizoglyphus Robini, it is distinct also from it. 
Authors include the species of this genus, together with others 
also generically distinct from it, under the common term ‘Tyro- 
glyphus, which according to Karpelles contains thirteen species. 
* Les Parasites et les Maladies Parasitaires,” 1880, p. 138. 
