230 



THE AMElilCAK MONTHLY 



[December, 



extrudes four additional caudal setae, 

 and thus has twice as many as the 

 normal complement. Some of the 

 books state that at a certain stage in 

 the tadpole's development the tail 

 falls off, and I was prepared to ac- 

 cept, in advance of ocular demonstra- 

 tion, this incorrect teaching in con- 

 nection with the four old setae, al- 

 though nature never seems wasteful. 

 But the treatment of the tail by the 

 tadpole is the treatment of these setae 

 by the infusorian. They are ab- 

 sorbed ; not all at the same time, nor 

 yet all in regular sequence, but when 

 the newly extruded seta is completely 

 formed then the old one is gradually 

 merged into the zooid's body ; the 

 more profusely fimbriated, being more 

 complicated, are the last to appear 

 and the last to be absorbed. 



Cyclidium litomesum^ sp. nov. — 

 (Greek, litos^ smooth ; meson ^ the 

 middle.) 



Body ovate, somewhat compressed, 

 longitudinally striate, the length about 

 two and one-half times the width, the 

 extremities subequally rounded ; dor- 

 sal surface convex, with a slight sub- 

 central concavity, the ventral one 

 flattened, somewhat concave ; oral 

 aperture situated slightly behind the 

 centre of the ventral surface ; the lat- 

 eral and dorsal cuticular surfaces of 

 the central region of the body entirely 

 naked ; setse of the anterior region 

 fine, numerous, their length equalling 

 or exceeding the width of the body, 

 the setae posteriorly situated diverse 

 in length, several of them exceeding 

 the length of the entire zooid ; con- 

 tractile vesicle postero-terminal ; oral 

 velum or hood large, its width equal- 

 ling that of the body. Length of the 

 body ^-1^ inch. Habitat. — Pond water 

 with Cer atop hy Hum. 



This form is distinguished from all 

 other members of the genus by the 

 extreme length of the posterior setae, 

 and by the unclothed central region 

 of the zooid. It is shown in Fig. lo, 

 magnified 420 diameters. The ante- 

 rior setag have the rigid aspect of 

 those of Pleuronema, rather than the 



usual appearance of those of the other 

 members of this generic group. 

 o 



Note on the Structure of the Scales 

 of Butterflies.* 



BY DR. ROYSTON PIGOTT, M. A., 

 F. R. S.,'f. R. a. S. 



' The gilded summer flies are nu- 

 merous as leaves in Vallombrosa.' 

 No I'ecess of the forest so obscure but 

 there the winged messengers are seen 

 to sport and play. Each summer 

 sunbeam lights up the gorgeous hues 

 of those bright creatures which even 

 the sombre Dante has named ' angel- 

 ical,' adorned with hues 



' Which make the rose's bkish of beauty pale 

 And dim the rich geranium's scarlet blaze.' 



Nor is the internal structure of these 

 angelical creatures' wings less en- 

 dowed with a rare beauty of sym- 

 metry and splendor. The resources of 

 a divine art of construction have re- 

 sulted in strength and lightness, grace 

 in action, elegance in repose, bril- 

 liance in effect, delicacy of combina- 

 tion, yet tubes, membranes, and, 

 above all, what I have ventured to 

 term organic molecules, evolve these 

 mysterious wonders, under the all- 

 pervading laws of undulatory vibra- 

 tion among the almost inconceivably 

 small wavelets of light. You all may 

 have noticed in your childish sport 

 the exceeding loveliness of the sun- 

 gilded soap bubble. At the thinnest 

 spot of the film — the highest just be- 

 fore bursting — a black spot arises ; 

 here the thickness of the material is 

 just about 1-1,000, 000th of an inch. 

 No light is reflected there. A series 

 of ringed colors show themselves in 

 many orders. The instrument before 

 you, which I constructed for the 

 Royal Society, exhibits all these beau- 

 tiful color phenomena. A film of 

 air or oil will each do equally well. 

 This thickness is regulated by a screw 

 and by wheel work ; the thickness 

 can be measured to a much less size 

 than the i -100,000th of an inch. It 



♦Read before the Natural History Society, East- 

 bourne. Reprintrd from the Eng. Mechanic. 



