1880.] Zoology. 375 
upon the number but also on the volume and weight of the cells. 
Dr. Minot therefore discusses the laws which govern the varia- 
tions of the size of cells. The relations of growth to the size of 
animals is next considered, the conclusion being drawn that the 
rapidity of the senescence determines the size of the animal, 
because the more rapidly the frequency of the cell divisions dimin- 
ishes, the sooner will growth cease and the smaller will the ani- 
mal remain, so that in this respect senescence exercises a funda- 
mental influence. This, is, we believe, the only scientific attempt 
to explain the reason why animals are of different sizes. Finall 
by a novel reasoning the conclusion is drawn, that although the 
animal grows in three dimensions, yet the growth of the cells is 
confined to two dimensions of space. For the detailed arguments 
supporting the author’s conclusions, the original article must 
consulted. í 
SCOLOPENDRELLA AS THE TYPE OF A NEW ORDER OF ARTICU- 
LATES (SYMPHYLA). — In examining a series of specimens of 
for their reception. The new group may be characterized in 
accordance with my observations as follows : 
Head essentially insectiform, or, more specifically, like that of 
Campodea, with mandibles, maxille and apparently a ligula. The 
labrum and labium are well defined, and the former is separated 
rom the epicranial pieces by a well-marked suture. Antennæ 
14-28 articulate. Body with thirteen segments (exclusive of 
head), to which are appended not more than twelve pairs of five- 
Jointed legs, each terminated by a pair of claws, as in insects. At 
the bases of each pair of legs a pair of simple hairy appendages are 
attached, except to the first or postcephalic: these are fully three 
times as large in S. gratie as in the other species. Caudal stylets 
in a single pair, tapering, unjointed. : 
Genital orifice on the ventral side of the body opening on the third 
or fourth body-segment in both sexes. In one sex the opening is a 
simple pore, in the other a /ongitudinal cleft, closed by means of 
an oblong chitinous piece on either side, the two together occu- 
pying a subquadrate space. Heart, dorsal; ¢vacheal system repre- 
sented by a series of simple tubular arches, without a spiral filament, 
which arise from openings on the ventral surface of the animal, 
inside the bases of the legs, widening and passing upwards to | 
apparently in close relation with the dorsal vessel, Intestine straight, 
with two very long, tortuous malpighian tubules opening into it 
at the posterior third (S. xotacantha). 
The genital glands, as well as the nervous system, I have not 
made out with any degree of certainty. The muscles are dis- 
