. Economic entomology . CASE Professor Owen considers that it represents the lowest organised form of the class Arachnidae and that it makes a transition from the Anellids to the higher articulates. If an Acarid it comes nearer the Sarcoptidse than any other, and we have thought the present as proper a place as we could find for it. Still we own that it comes in awkwardly, and as Dean Swift once said, if the judicious reader can assign it a fitter place, we do here empower him to remove it into any other corner he pleases. The more important points of affinity are the struc- ture of the mouth
. Economic entomology . CASE Professor Owen considers that it represents the lowest organised form of the class Arachnidae and that it makes a transition from the Anellids to the higher articulates. If an Acarid it comes nearer the Sarcoptidse than any other, and we have thought the present as proper a place as we could find for it. Still we own that it comes in awkwardly, and as Dean Swift once said, if the judicious reader can assign it a fitter place, we do here empower him to remove it into any other corner he pleases. The more important points of affinity are the struc- ture of the mouth which is suctorial, the transversely stri- ated skin, and its larval de- velopment. The latter is hexapod. Its habits are in some re- spects similar to those of some of the Sarcoptidse. It is not a normal inhabitant of the hair follicles or sebaceous glands, but appears to make its way into them from without. Either the same or an allied species has been found in the contents of the pustules of a mangy dog, when they occurred in such abundance that thirty or forty were frequently seen in a single drop of pus. It has not been discovered whether the insect had anything to do with originating the mange, or had merely taken advantage of its previous existence to establish itself in the pustules, nor does it appear whether the instance referred to was an isolated case or not (see Owen's Lectures on Invert Comp. Anatomy, 2nd ed., p. 444). In 1872 Pennetier described a species which he named D. caninus (Bull. Soc. Rouen), which is probably the same as the above.
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