ZOOLOGY AND BOTANY, MIOKOSCOPY, ETC. 501 



fibre ; tlie cylinder axis of this having penetrated into the cone, divides 

 into two chief branches, which give off the secondary ones, and these 

 divide dichotomously a number of times ; there is therefore a terminal 

 ramification analogous to what obtains in Vertebrates ; nothing like 

 this has ever yet been suspected of Arthropods, and it has been found 

 that just as there are differences in Vertebrates so similar differences 

 are to be seen in insects. 



M. Viallanes then treats of the phenomena of histolysis, and 

 concludes with an account of histogenesis, discussing the integument 

 and the muscular system as elaborately as we have reported him to 

 deal with the eye. 



Markings on Podura Scales.* — Dr. A. Y. Moore agrees that the 

 markings on Podura scales are caused by spines. These are attached 

 to the scales, not at the small end only, but by nearly the whole of 

 their under surface. If they were attached at the end, it is highly 

 probable, he thinks, that they would become broken or bent from 

 their normal position by a slight rub, whereas scales are found which 

 have been scratched and the spines still remain, but in an injured 

 condition, A woodcut is given of spines X 7600 by a Spencer im- 

 mersion l-6th in. objective. 



Mr. E. Hitchcock also refers f to some photographs by Dr. J. W. S. 

 Arnold, made by sunlight with a l-26th in. Wales objective, the magni- 

 fication in two instances being 2470 and 2740 diameters respectively. 

 A woodcut shows not only the appearance of the test Podura scale but 

 also a portion of a scale of Degeeria domestica " so closely allied to 

 Podura that it may be fairly assumed the structure of its scales is the 

 same." Several detached spines of the latter are shown, separated by 

 a fortunate accident, enabling us to see the separate spines, " thus 

 proving that they have an existence, and disproving some views that 

 have been advanced in the past concerning the structure of the scale." 



It will be remembered that the spines of Podura have been 

 separated from the scales by an electric spark, so that they could be 

 seen in a similar manner. 



)3. Myriopoda. 



Dermal Appendages of Polyxenus.l — The different forms of 

 hairs in P. fascicularis are described and , figured by Scudder ; those 

 upon the body-joints varying from club-shaped spines, furnished with 

 several rows of flattened teeth, to sabre-shaped spines, serrate on the 

 convex side. The posterior extremity of the body is provided with a 

 pair of cylindrical fascicles, resembling those of the larva of Anthrenus, 

 but composed of very curiously formed bristles, shaped like an elon- 

 gated fish-hook, the shaft gently curved, and the tip recurved and 

 apically barbed. The shaft is armed with delicate spinules, and the 

 crook furnished on the concave side with a few spatulate, drooping 

 appendages. 



* ' The Microscope,' ii. (1883) pp. 186-8 (3 figs.). 



t Amer. Mon. Micr. Journ., iv. (1883) pp. 101-2 (1 fig.). 



% Proc. Bost. Soc. Nat. Hist., xxii. p. 67. Cf. Science, i. (1883) p. 371. 



