66 MR. NEWPORT ON THE ANATOMY AND DEVELOPMENT 



pound eye than in the single. The result of these two conditions is, that the compound 

 eye is fitted for viewing objects at a considerable distance, but with little magnifying 

 power ; while the ocellus has great magnifying power, but is fitted only for viewing near 

 objects. The male with his single eyes may thus be regarded as acute, but short-sighted, 

 the very opposite of his partner. But this condition is essential to him, and fully suffi- 

 cient, if, as presumed, the greater portion of his existence is passed in a closed cell, not 

 half an inch in diameter, and from which perhaps he never wanders more than to the 

 distance of a few inches. But stemmata or ocelli only would be insufficient for the other 

 sex, who has not only to seek out the proper locality for her eggs, but also to elude the 

 vigilance of the bee in whose nest she is seeking to introduce her own progeny. Instead, 

 therefore, of mere stemmata, the eyes of the female are multiplied, and occupy, as in most 

 other perfect insects, a large portion of the surface on each side of the head. Each of 

 these aggregated eyes has a much greater length of sight, or distance of vision, than is 

 afforded by the different structure of stemmata ; while the multiplicity of these organs at 

 one spot supplies to the insect at once long focal distance, or long-sightedness ; and their 

 multiplicity more than compensates for the narrowness of the field of each cornea. 



The conclusions, then, which are deducible from the structure of the organs of vision 

 seem to be, that whenever an insect is provided only with stemmata, the habits of the 

 species, in that state of existence, are restricted to a few objects or requirements ; or that 

 the species is limited in perception and locality ; while, on the contrary, when the organs 

 of vision are multiplied and aggregated to form what we designate a compound eye, as in 

 the imago state of most perfect insects, the field of vision, as well as the focal distance, or 

 length of sight, and with these the range of the insect, are greatly extended. 



Other facts in the comparative anatomy of this parasite confirm these conclusions. The 

 short closed wings of the male, as noticed by Mr. Westwood in regard to the undescribed 

 insect Mellitobia *, contrasted with the wings of the female, lead us to infer that the 

 former sex rarely or never employs them in flight, and confirm the opinion that impreg- 

 nation is the sole requirement for the male, and is effected within the cell. 



This condition of the sexes affords a remarkable contrast to that of Stylops, which I for- 

 merly had the honour of bringing before the notice of this Society, Jan. 19, 1847 f. In that 

 genus, as will be remembered, the worm-like female is sought out by the active male, in 

 which the organs of vision, as in the equally active males of the Hive-bee and Glow-worm, 

 are enormously multiplied, yet merely for one single act of existence — the continuation of 

 the species. 



Thus it may be seen that under every form of body, and of each individual organ, the 

 special anatomy of a species is an index to its natural history and economy. 



The second Chalcididous parasite, which I have found in the nest of Anthophora, is an 

 insect of different character from the one just described, but equally illustrates the gene- 

 ral views now proposed. 



* Compare Mr. Westwood's remark on M. Audouin's insect above referred to, Introduction, &c, vol. ii. p. 160. 

 f Linn. Trans, vol. xx. p. 347-349. 



