The skull is abnormally thick and the cerebral capacity small.
As in other Gastropoda Anisopleura, this shell-sac may abnormally develop a plug of chitinous matter, but normally it flattens out and disappears, whilst the cap-like rudiment of the permanent shell is shed out from the dome-like surface of the visceral hump, in the centre of which the shell-sac existed for a brief period.
In her childhood she was noted for her abounding physical energy; but her vivacity, so far from being tainted by any coarse or unfeminine trait, was the direct outcome of an abnormally sensitive nervous temperament.
Sometimes various lichens occur abnormally in such unexpected habitats as dried dung of sheep, bleached bones of reindeer and whales, old leather, iron and glass, in districts where the species are abundant.
The heart's action is feeble, the pulse being small, irregular and often abnormally slow.