l2 4 NATURAL SCIENCE [August 



volume, when the student would have been in a position to attack the 

 pn »1 ilems ra ise< 1 with fuller knowledge of the facts. Prof. Packard goes 

 with the inaj< irity of those zoologists who discussed the arthropods some 

 time ago in the pages of Natural Science, considering them a group of 

 multiple origin which '-may eventually be dismembered into, at least, 

 three < >r f< iur 1 tranches." In the " provisional genealogical tree," which 

 ■ may serve to show in a tentative way the relations of the classes," 

 the Tiilobita 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 branehiates and tracheates, considering that the air-tubes of 

 spiders and mites show no necessary relationship between those 

 animals and the insects. Peripatus and Scolopendrella appear in the 

 direct line of the ancestry of insects, the niyriapod stem branching off 

 below Scolopendrella. The Diplopoda and Chilopoda are given as 

 separate classes in the tree, though in the text the author seems 

 inclined 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 Pauropus. 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 Scolopendrella "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 

 tin' 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 Lpwne 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 jaw-. The author states that Miall and Denny 

 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 



