666 Recent Literature. | September, 
cal process in Blatta. He compares these structures with the 
second branch of the bifid antennz of Pauropus. We may add 
that in certain coleopterous larvz there are similar movable pro- 
cesses. These may be found to exist in other low or larval 
insects ; but while interesting and suggestive, we scarcely see the 
need of going so far as to homologize them with the bi-flagellate 
antenne of the Crustacea. These attempts are due to the hypoth- 
esis that the insects have been derived from the Crustacea, instead 
of what has seemed to us the better grounded view that the two 
classes have independently arisen from the worms, and also it is 
forcing nature into a straight jacket to attempt to institute too 
though he adds that the joints are not movable. We have found 
what we suppose to be less distinct traces of an articulation in the 
mandible of Campodea. He concludes that the mandibles of the 
cockroaches are compound structures, “each made up of three 
(or four) such joints as are to be seen in Machilis.” 
Our author thenasks, “Are the mandibles of insects and myria- 
pods, like the jaws of Peripatus, modifications of walking legs ? 
He answers the query in the negative, and his reasons for his con- 
clusion are apparently due to the influence of the hypothesis that 
insects are derived from Crustacea and not first hand from the 
worms. He judges that the mandibies of the higher Thysanura 
and the cockroaches as well as the myriopods “have resulted 
from the direct modification of such a biramous appendage as 15 
seen in the earliest (nauplius) condition of many crustaceans. 
Embryology shows conclusively that the mandibles and in fact 
all the appendages of the head of both Crustacea and insects arise 
in the same manner and have the same form as the thoracic ap- 
pendages. Would this not indicate that both arose from worms In 
which the rami and tentacles are obviously identical in form, and 
but slightly differentiated in function; and that the two classes 
followed distinct developmental paths, one with limbs adapted for 
swimming, as in the nauplius, with limbs all alike and no head 
differentiated from the rest of the body; while the terrestrial an- 
cestor of the insects at once assumed what we have called tne 
` Leptus condition, having a head separate from the rest of the 
Another point of interest studied by Mr. Mason is the nature 
