1890.] 
507 
[Packard. 
rally far more than the genera of Geometrids and of Noctuidae, and 
the number of species is less. The two latter families probably 
arose from the great specialization of type in Tertiary times ; while 
evidently the great group or superfamily Tineidse and allied forms, 
in some of which the mandibles still persist , 1 and which in other 
features (besides having as in Nepticula and Phyllocnistis nine 
pairs of abdominal legs 2 ) show their affinity to the Trichoptera and 
Mecaptera, originated at an earlier date. As is well known the 
Cretaceous land was covered with forests of oaks, liquidambars, 
maples, willows, sassafras, dogwood, hickory, beech, poplar, wal- 
nut, sycamore, laurel, myrtle, fig, etc., at, or soon after, the close 
of the Laramie epoch, and this may have been the time, if not ear- 
lier in the Mesozoic, when in all probability the low-feeding cater- 
pillars of that time began, perhaps through overcrowding, to desert 
their primitive herbaceous food plants and to ascend trees in order 
to feed on their leaves. 
Darwin 3 has made the significant remark “ that organic beings, 
1 Dr. A. Walter has discovered the presence of minute rudimentary mandibles in the 
European Micropteryx caltella, Tinea pellionella , Tineola biseliella, Argyresthia niti- 
della , Crambus tristellus , and two genera of Pterophoridae (Sitzungsb. Jena, Ges. fur 
Med. u. Naturwiss. 1885). I have also detected them in Coleophora coruscipennella and 
in another Tineid of a genus as yet undetermined. 
2 The larvae of Phyllocnistis have no thoracic legs, but have eight pairs of membra, 
nous retractile abdominal legs, and an anal pair. (American Entomologist, in, 256.) 
Mr. H. T. Stainton kindly informs me that the larvae of Nepticula have no thoracic legs 
“but possess nine pairs of abdominal legs,” which however bear no hooks; “they look 
like so many fleshy prominences.” 
3 The Variation of Animals and Plants under Domestication, second edition, revised, 
London, 1888. In the same work Darwin says: “ Nathusius states positively (p. 99, 
103), as the result of common experience and of his experiments, that rich and abun- 
dant food, given ( uring youth, tends by some direct action to make the head [of the 
pig] broader and shorter, and that poor food works a contrary result.” 
Darwin also states that “ the nature of the food supplied during many generations 
has apparently affected the length of the intestines, for according to Cuvier, their 
length to that of the body in the wild boar is as 9 to 1,— in the common domestic boar 
as 13.5 to 1,— and in the Siam breed as 16 to 1 ” (lb., 77). See also the cases mentioned 
by Semper in his Animal Life, etc., pp. 60-62, and Neumayr’s Stamme der Thierreichs, 
1889, 123. Virchow claims that the characters of the skull depend on the shape of the 
jaw, this being due to differences in food; and here might be quoted the witty remark 
of Brillat-Savarin, “ Dis-moi ce que tu manges, je te dirai ce que tu es.” 
The most remarkable case and one directly applicable to our subject of the probable 
cause of the growth of spines is that cited by Prof. J, A. Ryder. “Even certain species 
of fishes, when well fed and kept in confinement, not only spawn several times during 
a season, instead of only once, as I am informed by Dr. W. H. Wahl, but also when 
kept from hibernating, as he suggests, tend to vary in the most astounding manner. 
The wonderful results of Dr. Wahl, attained in the comparatively short period of six 
years, show what may be done in intensifying the monstrous variations of Japanese 
gold-fishes, through selection, confinement in tanks and aquaria, with comparatively 
limited room for swimming, plenty of food, etc., all of which conditions tend to favor 
