124 NATURAL SCIENCE [August 
volume, when the student would have been in a position to attack the 
problems raised with fuller knowledge of the facts. Prof. Packard goes 
with the majority of those zoologists “who discussed the arthropods some 
time ago in the pages of Tatural Science, considering them a group of 
multiple origin which “may eventually be dismembered into, at least, 
three or four branches.” In the “ provisional genealogical tree,” which 
“may serve to show in a tentative way the relations of the classes,” 
the. Trilobita are separated from the Crustacea and placed near the 
common ancestors of the Merostomata (including Limulus) and the 
Arachnida. Prof. Packard therefore rejects the division of arthropods 
into branchiates and tracheates, considering that the air-tubes of 
spiders and mites show no necessary relationship between those 
animals and the insects. Periputus and Scolopendrella appear in the 
direct line of the ancestry of insects, the myriapod stem branching off 
below Scolopendrella. The Diplopoda and Chilopoda are given as 
separate classes in the tree, though in the text the author seems 
inchned to defend the old Myriapoda as a natural class against the 
views of Kingsley and Pocock. Most zoologists will be surprised to 
see that the millipedes are placed nearer to the insects than are the 
centipedes ; Prof. Packard still attaches considerable importance to 
the six-legged larvae of Julus and Pawropus. There is a short 
account of the anatomy of Peripatus ; in the points which separate it 
from the worms it is surprising to find no mention of its reduced 
coelome and secondarily-formed body-cavity. The description of 
Scolopendrella is fuller—a valuable summary for English readers of 
the recent researches of Haase, Grassi, and Schmidt on this very 
interesting creature with an original figure of its internal anatomy. 
But the statement that Sc colopendr ella “seems to be, like other archaic 
types, cosmopolitan in its distribution,” is puzzling, since a restricted 
or discontinuous distribution is certainly characteristic of most archaic 
forms of life. 
A synopsis of the characters of insects generally introduces 
the section of the book devoted to anatomy. The statement here 
that the labium is formed of the two laciniae of the second maxillae 
fused together seems a curious slip, and the saw-fly grubs are not 
mentioned among the larvae with functional abdominal limbs. In 
the detailed account of the external structure of insects, advantage is 
taken of the latest researches on the mouth-organs, attention being 
specially directed to the mandibles and first maxillae in the primitive 
Lepidoptera. A fuller treatment of the piercing and sucking mouth- 
organs of the Diptera and Hemiptera would have been desirable ; the 
statement is made that functional mandibles are lacking in the latter 
order, but Prof. Packard does not say if he agrees with Lowne in 
regarding the lancets usually identified with those appendages as 
belonging to the maxillae. The epipharynx and hypopharynx 
are treated at considerable length—a valuable feature in the work, 
as these organs usually receive much less attention from entomologists 
than the paired jaws. The author states that Miall and Denny 
are mistaken in denying the presence of an epipharynx in the 
Orthoptera. He believes that the insect head consists of at least 
six segments, including the primitively pre-oral lobe which carries 
the eyes and ocelli, and the intercalary or tritocerebral lobe between 
