ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 209 



stomach varies in character ; in Machilis (and Lepisma ?) there are 

 depressed spots which are centres of regeneration. In Campodea and 

 Macrotoma plumbea [wm] these spots are wanting. The Thysanura 

 have salivary glands, but it is not yet certain that these organs are 

 generally present in the Collembola. Malpighian vessels are found in 

 Machilis, Lepisma, and Nicoletia, but wanting in Japyx and the Collem- 

 bola ; Campodea is in this respect an intermediate form, for it has 

 diverticula. So far as is known the Thysanura have nine pairs of 

 ostia in the dorsal vessel ; such representatives of the Collembola as 

 were examined have only five pairs ; the blood is always coloured 

 yellow, and contains blood-corpuscles. In both groups tracheaB are 

 found, but they may be wanting in the Collembola, and, where present, 

 are always feebly developed. In some of the Thysanura the tracheae 

 do not form anastomoses ; the stigmata of these forms are thoracic and 

 abdominal in position ; in the Collembola they are found on the head. 



The generative organs of the two groups show some differences. 

 The female gonads of Machilis, Lepisma, and Nicoletia agree in most 

 points ; there are two oviducts, and with each a varying number of 

 ovarian tubes are connected ; they have an ovipositor which always 

 belongs to the eighth and ninth segments of the abdomen. Both male 

 and female gonads in Campodea exhibit considerable resemblance to 

 those of the Collembola ; in the latter these organs are always two 

 simple tubes. 



The author thinks that neither group can be placed in any of the 

 orders of Insects, for the complete absence of wings and of any sign of 

 metamorphosis forbid it. He agrees with P. Mayer and F. Brauer in 

 speaking of them as Apterygogenea as opposed to the other Insects, 

 which are Pterygogenea. He regards the Thysanura as a distinct 

 family from the Collembola ; the former are divided into the Lepismidse 

 and the Campodeid^, and for the latter he accepts Tullberg's divisions 

 of Sminthurinse, Templetoniinae, and Lipurinse. He concludes with a 

 tabular statement of the various points of difference. 



j3. Myriopoda. 



Classification of Myriopoda.* — Mr. C. S. Kingsley doubts the 

 homogeneity of the group of Myriopoda, and considers that the features 

 common to the Chilopoda and Chilognatha are possessed by all other 

 air-breathing Arthropods. The best definition for the wbole group will 

 probably run as follows : — The Myriopods are air-breathing Arthropods 

 with elongate bodies and more than three pairs of legs. 



The Chilognatha or Millipedes have a head which bears, besides 

 antennae, only two pairs of appendages; all but the more anterior 

 segments of the body carry two pairs of appendages ; and the bases of 

 these legs are placed close to one another. The Chilopoda have three 

 pairs of gnathites, each segment has but a single pair of legs, and these 

 are widely separated at their base. The stigmata of Chiloj)ods are 

 placed at the sides of the body, above and outside the line of the legs ; 

 in the Chilognaths they are placed beneath or even in the coxal joints 

 of the legs. The most marked points of difference are to be found in 

 the generative organs, Chilopods are very closely allied to Insects ; 

 the Chilognaths seem to stand alone, Peripatus being nearer the annelid 

 than the hexapod stock. 



* Amer. Natural., xxii. (1888) pp. 1119-21. 



