70 MR. NEWPORT ON THE ANATOMY AND DEVELOPMENT 



Postscript to the foregoing Section of this Paper. 



Read May 1, 1849. 



I am desirous of appending a few remarks to the section of this paper that has already- 

 been communicated to the Society, before proceeding with the remainder. 



These refer to the second bee-parasite described, and provisionally named Monodonto- 

 merus nitidus. The parasitism of insects of this genus on Anthophora had not previously 

 been ascertained. M. obsoletus had been suspected of infesting the genus Osmia *, like 

 one of its affinities t, but its larva, so far as I am aware, was unknown. I found the 

 larva of M. nitidus in the nests of Anthophora, on the 27th of September, 1847, and men- 

 tioned the fact to an entomologist, Mr. F. Smith, who, some time afterwards, as he him- 

 self informed me, obtained specimens of it from the same locality. From a note on its 

 habits, which he has recently communicated to this Society J, it appears that the larva is 

 carnivorous, and feeds on the bee-larva, and not on its food, as I had believed. I am 

 thankful for this correction of observation. The mistake arose in my haste to furnish 

 part of this paper for reading to the Society by a given time, which obliged me to forego an 

 examination of the parts of the mouth, which are difficult to observe, and compelled me to 

 rely on the appearance of the faeces, and on the fact of having found my full-grown speci- 

 mens in the cell of the bee with the dried-up remains of the bee-larva. I have now made 

 the required observations on the oral organs, and also have microscopically examined the 

 contents of the digestive apparatus, and these lead me to agree with Mr. Smith in regarding 

 the larva as carnivorous, and not as pollinivorous. The mandibles are slender, arched 

 and acute, and are fitted only for piercing, and not for comminuting food ; the labium and 

 maxillae are thick, large and membranous, somewhat like those of the larva of Paniscus. 

 The contents of the digestive apparatus I found to consist of large and small nucleated 

 cells, consolidated together, and darkened in appearance, conditions induced probably by 

 admixture with secretions from the parietes of the apparatus during digestion. 



Thus further examination of this larva tends but to confirm, instead of to confute the 

 general view which I have constantly maintained, — that structure, when carefully and 

 accurately investigated, is an infallible index to function and habit. My incorrectness in 

 opinion as to the particular kind of food of the larva of Monodontomerus was the result of 

 hurried and incomplete inquiry, and it is now rectified by direct observation on the habits 

 of the insect, and by closer attention to its anatomy. Yet the main object of this paper 

 was but little affected by the error, my aim being to show not merely that Hymenopte- 

 rous parasites may differ in their kind of food, but the more general fact of a concordance 

 between structure and kind of life ; — and also that whether the Hymenopterous parasite is 

 shut up in the same cell with an insect that continues to feed, or whether it preys on the 

 surface or interior of such insect, its alimentary canal is closed and incomplete until it has 

 ceased to take food and has acquired its full size, when the canal becomes perforated, and 

 allows a passage for the ejection of the refuse of nutrition ; the necessity for this late com- 

 pletion of the organs of digestion having reference to the preservation of the food of the 

 parasite in a condition fitted for its proper nourishment. 



* Westwood's Introduction, &c, vol. ii. p. 160. t Id. % Proceedings, vol. ii. p. 29. 



