brilliant metallic spot. When the sun shines on them the larvae seem to
be covered with diamonds. These metallic spots at the base of the spines
are also seen on Pernyi, Yama mai, Mylitta, and other species of the
genus Antheraea, all having a closed cocoon, but none of these have so
many as Polyphemus.

The cocoons of the species of the genus Actias are closed, but the larvae
have not the metallic spots of the species of the genus Antheraea.

_Samia Gloveri_.--Three North American silk-producing bombyces, very
closely allied, have been mentioned in my previous reports; they are;
_Samia ceanothi_, from California; _Samia gloveri_, from Utah and
Arizona; and _Samia cecropia_, commonly found in most of the Northern
States--the latter is the best and largest silk producer. Crossings of
these species took places in 1880, and, as I stated before, the ova
obtained from a long pairing between a Ceanothi female with a Gloveri
male, were the only ones which were fertile. The Gloveri cocoons
received in 1880 were of a very inferior quality, and produced moths
from which no pairings could be obtained, although some crossings took
place. In 1881, the Gloveri cocoons, on the contrary, produced fine,
healthy moths; yet only five pairings could be obtained, with about one
hundred cocoons. Besides these five pairings, a quantity of fertile
ova were obtained by the crossings of _S. gloveri_ (female) with _S.
cecropia_ (male), and Cecropia (female) with Gloveri (male). No success,
so far as I know, was obtained with the rearing of the hybrid larvae; the
rearings of the larvae of pure Gloveri were also, I think, a failure,
only one correspondent having been successful; but some correspondents
have not yet made the result of their experiments known to me. The larvae
of _Samia cecropia, S. gloveri_, and _S. ceanothi_, are very much alike;
and hardly any difference can be observed in the first two stages. In