OF WASHINGTON. 31 
mens of a young Helix, evidently born in that locality. The bark of the 
tree near these larvae was slightly decayed ; a stone pressing against the 
growing tree being the cause of this decay. Taking the larvae home to a 
breeding cage, they remained motionless for some days. Later, however, 
with increase of temperature, they showed signs of life by slowly crawling 
about, evidently with the view of fastening themselves more securely to 
pieces of bark, stones, etc. Their motion was very sluggish a Helix 
moving with the velocity of lightning express in comparison with them. 
The peculiar waxy appendages of the segments of this larva are not fleshy, 
as stated by Packard, but are hollow tubes and not flexible. The larva 
otherwise is well figured in the Guide. 
In the course of about ten days some of the larvae had transformed to 
pupa'. The pupa is formed inside of the larval skin, and no outward indi- 
cations are perceptible, excepting a slightly paler and more uniform white 
color of the larva; its shape does not change at all. A longitudinal slit 
along a subdorsal suture on each side is only revealed by pressing the larva. 
The white pupa is thus snuglv hid from view, and the resemblance to a 
skin of Oniscus is even more perfeqt than before. In six days a perfectly 
white imago would issue from one of these slits, leaving the empty pupal 
skin in the posterior part of the larval skin. The imago changed its color 
very rapidly ; first, to a very light sky blue ; later, the posterior portion of 
the wing-covers acquire a dark blue, and the anterior portion an orange 
color. The beetles are very sluggish for some time, but during the warm 
hours of the day would flv about quite actively. They freely copulated, but 
only one egg was obtained, which, being unfertilized, soon shrank up. He 
doubts that these larva are carnivorous, but thinks them to be vegetable 
feeders. 
Dr. Riley called attention to the similarity in structure and 
habit of the larva of Calopteron terminate to that of the Caenia. 
That of Calopteron is gregarious and lignivorous. He had also 
known Photinus pyralis to feed on snails. 
Mr. Mann explained at length the Dewey decimal system of 
classifying and arranging books. This system uses decimally 
cumulative Arabic numerals corresponding and attached to the 
divisions of a logical classification of subjects, in combination 
with an alphabetic index referring by number to the several di- 
visions, thus combining the advantages of logical and alphabetic 
classification without their disadvantages. It can be used in as 
great or little detail as desired, and is especially applicable to in- 
dices rerum and library shelf classifications. Its definite charac- 
ter renders it a standard, and it is already more widely in use 
than any other system of subject classification. Dr. Riley took 
the ground that, while the system is an admirable one for large 
