94 SELECTED NOTES FROM 



When very highly magnified, they appear, as shown at Fig. G^ 

 as rows of Uttle spheres, with irregular dumb-bell-like objects 

 between them, a space lying between two rows, with a row of 

 bristles on each space. I do not understand the " dumb-bells " ; 

 they are, perhaps, not solid, but merely illusory appearances, 

 caused by light refracted and reflected from the otoconia. 



Some idea of the smallness of the otoconia may be gathered 

 from the fact that Fig. G is magnified 630 diameters. In the 

 haltere on the slide under discussion the otoconia cannot be seen, 

 but their sheaths are plainly visible when the haltere is torn near 

 the base. Space and time will not permit me to fully discuss the 

 function of the so-called otoconia ; but I recommend all who can 

 to read what Mr. B. T. Lowne says on the subject in his valuable 

 work on the Blow-Fly. 



I have omitted to mention that at the end of most halteres 

 (and probably all) there is a flat, oval, more transparent portion 

 which seems peculiarly like the tympanic membrane in the ears of 

 mammalia. 



The insects from which the drawings of the haltere and oto- 

 conia were made are two of the best diptera for studying these 

 organs by. The common Blue-Bottle, however, shows these 

 organs as well as most insects. Frank J. Allen. 



Flea. — The muscles of this insect may be well shown by soak- 

 ing a freshly-killed flea successively in ether, water, weak spirit, 

 absolute alcohol, and oil of cloves, and finally mount in Canada 

 balsam without pressure. Frank J. Allen. 



Centipede. — Mr. West's careful drawings of the Centipede (PL 

 I., Figs. 3 — 10) are very interesting, and bears upon a subject 

 respecting which I should like to know more. In the first place, 

 is it to be regarded as an undoubted fact that the segments or 

 rings of insects are not multiplied as Mr. West states ? Audouin, 

 many years ago, in a paper published in the Annales des Sciences 

 Naturelles, endeavoured to show that each segment of the thorax 

 of insects was normally composed of four sub-segments. Now, I 

 have not had an opportunity of seeing this paper, and do not 

 know what reasons were adduced for such a conclusion ; but 

 certain phenomena connected with the thoracic appendages have 

 lately attracted much of my attention, leading forcibly to a similar 

 result. Audouin's views seem to have dropped completely out of 

 sight, for I nowhere find the number of segments in insects put 

 down at more than seventeen ; indeed, in all but recent treatises, 

 thirteen is quoted as the normal number, and it was only after 

 forming my own opinion on the subject that I became aware of 

 its coincidence with that of Audouin. 



I cannot here enter into the discussion of this subject. Suffice 



