1888, ] 203 (Packard. 
losoma, according to Metschnikoff, the larva has eight segments behind 
the head, the second segment footless ; in Polydesmus there are but seven 
body-segments, the second apparently being apodous, though it is difficult 
to determine with certainty from the drawing which of the three first 
segments is apodous. 
In two embryos of Julus multistrratus Walsh? kindly communicated to 
us by Prof. Riley, and which he assures us were freshly hatched right from 
the egg, the larve are much more advanced than in the freshly-hatched 
larve referred to ; still the second body-segment ts footless instead of the third; 
but there are seventeen segments, the Ist, 8d and 4th each bearing a sin- 
gle pair of legs; the 5th-10th segments each bearing two pairs of legs. 
In one of the three specimens, which was apparently a little longer out of 
the egg than the two others, there were five penultimate short secondary 
segments (11th-15th) on which there were rudiments apparently of but a 
single pair of legs to each segment, whereas Newport states that two pairs 
bud out from each segment, and while in Julus terrestris the new segments 
arise in sixes, in our species they arise in fives. In adult life a single pair 
of limbs arises from the second segment, and the first three segments each 
have but one pair of legs, the fourth having two as in the fifth and fol- 
lowing segments, 
It thus appears that the larval diplopod Myriopod is a six-footed Trach- 
eate, though neither its mouth-parts nor primary legs are directly homolo- 
fous with those of the Hexapodous insects. 
Looking at the embryo diplopod Myriopod from a deductive or specula- 
tive point of view, it doubtless represents or is nearly allied to what was 
the primitive myriopodous type, a Tracheate, with a cylindrical body, 
whose head, clearly separated from the hind body, was composed of three 
cephalic segments, one pair of antennex, succeeded by two postoral arthro- 
meres, the protomalal and deutomalal arthromeres ; while the hind body 
consisted of as few as seven arthromeres, whose scuta nearly met beneath, 
with three pairs of six-jointed legs distributed among the first four seg- 
ments. It is evident that the form represented by the adult is a secondary 
later product, and arose by adaptation to its present form. The embryo 
Geophilus, the only Chilopod whose embryology has been studied, leaves 
the egg in the form of the adult; it has, unlike the diplopods, no meta- 
morphosis. Its embryological history is condensed, abbreviated. 
But in examining Metschnikoft’s sketches, primitive Chilognath charac- 
ters assert themselves ; the body of the embryo shortly before hatching is 
cylindrical ; the sternal region is much narrower than in the adult, hence 
the insertion of the feet are nearer together, while the first six pairs of ap- 
pendages (the sixth apparently the first pair of feet of the adult) are indi- 
cated before the hinder ones. These features indicate that the Chilopoda 
probably arose from a diplopod or diplopod-like ancestor, with a cylindri- 
cal body, narrow sternites and with three pairs of legs, which represent 
those of the larval Chilognaths, the two anterior becoming the two pairs of 
malipedes of the present Chilopoda, Thus the first six appendages of the 
