Packard.] 
86 
[May 7, 
unlike that of the tarsus of the thoracic legs of insects in general, 
may not he an ill-founded one. 
The relation of parts was better seen in the young larvae of 
Orgyia leueostigma, 1 where, as in Parorgyia, the number of crochets 
is four in all the abdominal legs including the last or anal pair. On 
examining an alcoholic specimen without treatment with any re- 
agents the planta appears as at fig. 3. The two pairs of primi- 
tive crochets are seen to be rather wide apart and in relation with 
their respective retractor muscle, fig. 3, m. The grypogene or 
hook-forming organ, g , is seen to be bilobed, each lobe containing 
two rows of round distinctly nucleated cells, about eight in a row. 
The nature of these cells was a good deal of a puzzle until I 
examined a specimen which was about to moult. It had by acci- 
dent been allowed to partially dry and was then soaked in a prep- 
aration of oil of turpentine and carbolic acid with a little liquor 
potassse and stained with picro-carmine. 
On examining specimens thus treated under a -g Tolies objective, 
B eye-piece, the nature of the bilobed organ with its twenty-four to 
thirty-two round nucleated cells became manifest. Fig. 4 a repre- 
sents the planta seen from the inside with the grypogene, with four 
primitive crochets. The outer rows of cells have apparently began to 
break down and disappear or become absorbed, while the basal row r 
of cells are now elongated, have become acutely pointed at the end, 
while the contents have become a clear amber-colored fluid, destined 
to become the substance of the chitinous hooks. The nucleus of 
each incipient hook still persists. In fig. 4 b and 4 c, the basal 
row of cells are more advanced in development, now chitinous, 
while the outer row of cells have nearly disappeared. It is evident 
that at the next moult the incipient crochets will be added to the 
primitive four, and form the semicircle of curved crochet-like hooks, 
about ten or twelve hooks being added at the first moult. 
It thus appears that the abdominal legs show a decided tendency 
to be three-jointed ; that at their extremity they show a tendency 
to be bilaterally symmetrical and are thus more closely homolo- 
gous with the normal legs of insects than formerly supposed. 
Hence, the popular names “ false-legs” and “prop-legs,” signifying 
that these appendages are not true legs, are founded upon a misap- 
prehension. 
1 For some well preserved alcoholic specimens of this caterpillar in its first stage, I 
am indebted to Dr. C. V. Riley. 
