1893. ARACHNID AND INSECT DEVELOPMENT. 447 



" respiratory trumpets " on the prothorax. The air is admitted to 

 these through a series of small oval apertures, fine enough to keep 

 out water or dirt, if they are not closed (as may, perhaps, be the case) 

 by a transparent membrane. The abdominal segments bear dorsal 

 plates with spines, by means of which the pupa makes its way out 

 of the ground, before the fly emerges ; ventral pro-legs, corresponding 

 to those found in the larva, assist in this function. 



The structure of the stigmata of the grub of the Common 

 Cockchafer, as described by Herr Boas (8), recall the arrangement of 

 the respiratory trumpet of the Dicmnota pupa. The ordinary opening 

 of an insect stigma is found to be closed in this larva, and the insect 

 takes in air through minute pores in the " sieve-plate " surrounding 

 the normal aperture. In both cases we see the adaptation to an 

 underground life. 



The highly interesting pupa of a minute moth {Micropteryx) has 



been lately described by Dr. Chapman (g). This pupa lives in a 



very strong cocoon, several inches underground. It is remarkable 



among lepidopterous pupae in possessing a well-developed labrum, 



and mandibles which Dr. Chapman (allowing for the relative sizes of 



the insects) compares to those of a stag-beetle ! As is well-known, 



these organs are usually reduced to the merest vestiges in moths and 



their pupae. In the present case, the obvious use of these powerful 



jaws is to effect the escape of the pupa from its buried cocoon, before 



the emergence of the moth. The arrangement recalls what occurs 



in the Caddis-flies, and is another strong argument in favour of the 



primitive position of the Micropterygidse among Lepidoptera, the 



wing-neuration having already led to the acknowledgment of their 



affinities with the Trichoptera. Yet another fact which tells the 



same tale is that the pupa seems entirely incomplete (the limbs are 



not soldered to the body) and the moth escapes through a simple 



dorsal slit — an arrangement hitherto unknown among moths according 



to Dr. Chapman. 



REFERENCES. 



1. Lankester, E3. Ray. — Limulus an Arachnid. Quart. Journ. Micr. Sci., 



vol. .\xi., 1 88 1. 



2. Kingsley, J. S.^The Embryology of Limulus. Jouvn. Morphology, vol. vii , 



1892, pp. 35-68, pis. v., vi. ; vol viii., 1893, pp., 195-268, pis. x.-xiii. 



3. Kishinouye, K. — On the Development of Limulus longispiua. Journ. Coll. Sci. 



Univ. Jap., vol. v., 1891. 



4. Patten, W. — On the Morphology and Physiology of the Brain and Sense-Organs 



of Limulus. Quart. Journ. Micr. Sci., vol. xxxv., 1893, pp. 1-96, pis. 1-5. 



5. Pocock, R. I. — On the Classification of the Tracheate Arthropoda. Zool. Anz., 



vol. xvi., 1893, pp. 2.'Jl-2J^. 



6. Wheeler, 'W. M. — A Contribution to Insect Embryology, Journ. Morphology, 



vol. viii., 1S93, pp. i-iGo, pis. i.-vi. 



7. Miall, li. C. — Dicranota : a Carnivorous Tipulid Larva. Trans. Ent. Soc. Loud., 



1893, pp. 235-253, pis. x.-xiii. 



8. Boas, J. E3. Y. — Ueber die Stigmen der Melolontha Larva. Zool. Anz., vol. xvi., 



1893. pp. 389- 391. 



9. Chapman, T. A. — On a Lepidopterous Pupa {Micropteryx purpurella) with 



functionally active Mandibles. Trans. Ent. Soc, 1S93, pp. 255-265. 



Geo. II. Carpenter. 



