. The Annals and magazine of natural history; zoology, botany, and geology. Natural history; Zoology; Botany; Geology. Rev. T. Ilincks on the Pohjzoan Avicularium. 23 Fio-. Fiff. .3. But in s]")ecimens from tlie Queen Charlotte Islands, which have been placed in my hands by Dr. G. M. Dawson, of the Canadian Geological Survey, the appendage occurs in a very different guise : so far as the mandibular portion is concerned, its appear- ance is completely changed, and it is at gnce evi- dent that a very important structural modification has been effected. The mandible has altogether lost i
. The Annals and magazine of natural history; zoology, botany, and geology. Natural history; Zoology; Botany; Geology. Rev. T. Ilincks on the Pohjzoan Avicularium. 23 Fio-. Fiff. .3. But in s]")ecimens from tlie Queen Charlotte Islands, which have been placed in my hands by Dr. G. M. Dawson, of the Canadian Geological Survey, the appendage occurs in a very different guise : so far as the mandibular portion is concerned, its appear- ance is completely changed, and it is at gnce evi- dent that a very important structural modification has been effected. The mandible has altogether lost its lid-like character, and is now a very tall S^ membrano-chitinous appendage, commonly ex- ceeding in length the entire cell, broad at the base, and tapering off to a fine point above, where it is slightly curved (woodcut, fig. 3). The expanded trian- gular portion below, which represents the normal mandible, has undergone little change ; but its ofiice now is to support the vibraculoid appendage which I have described. Just above the point wiiere the extremity of the true mandible begins to expand into the 5'»r^<?^-vibraculum, there are two small spinous projections; these mark the commencement of a mar- ginal extension of the vibraculum, whicli runs along each side from this point to the apex, diminish- ing in width as it approaches the top. This marginal increment curls upward, and gives a channelled appearance to the appendage. The ?^" whole structure is of a membrana- ^^^t^- ceous character; and there is always a slight twist near the base of it. When the transformed mandible is at rest on the fixed beak, the free portion of it occupies a suberect position. The modification is not confined in this case to the man- dible, but extends to other elements of the structure. In the first place, the rising on which the organ is placed is mucli laro-er and more prominent than in the normal form, and recalls the vibracular cell which supports the movable seta in Mastiqopho
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