54- Zoological Society. 



They seem, however, to show more decisively that plants do, 

 to a certain extent at least, possess a power of selection, and that 

 the earthy constituents which form the hasis of their solid parts 

 are determined as to quality [kind?] by some primary law of nature, 

 although their amount may depend upon the more or less abundant 

 supply of the principles presented to them from without. 



The conclusion of Mr. Westwood's Monograph on the Genus 

 Diopsis was also read. The subject of this paper is a remarkable 

 group of two-winged flies, having the sides of the head produced into 

 two long and slender processes, at the extremity of which the eyes 

 and antennae are placed. In this paper the author has given the 

 characters of the genus at great length, has more than doubled the 

 number of species, and has noticed the analogous structure of other 

 pedunculated-eyed animals. He has divided the genus into four 

 sections. A. wings with an abbreviated stripe near the tip, including, 

 1. D. ichneumonea, Linn., Tropical Africa; 2. D. collaris, Westw. 

 Senegal ; 3. D. pallida, Westw., habitat unknown ; 4\ D. nigra, Illi- 

 ger, Sierra Leone. — B. wings with a terminal spot. 5. D. apicalis, 

 Dalm., Sierra Leone; 6. D. tenuipes, Westw., Senegal ; 7. D.indica, 

 Westw., East Indies; 8. D.assimilis, Westw., habitat? 9. D. abdo- 

 minalis, Westw., habitat ? 10. D. fumipennis, Westw., Senegal. — 



C. Wings without spots. U. D. signata, Dalm., Sierra Leone; 

 12. D.Jasciata, Gray, habitat ? 13. D. macrophihalma, Dalm., Sierra 

 Leone; 14-. D.thoracica, Curt. MSS., Westw., Africa ; \5. D. ob- 

 scura, Westw., Sierra Leone ; 16. D. confusa, Weid., Angola. — 



D. Wings with several entire fasciae; 17. D. Dalmanni, Weid., Java; 

 18. D. Sykesii, Gray MSS. Westw., East Indies; 19. D. brevicornis, 

 Say, North America. 



ZOOLOGICAL SOCIETY. 



July 23. {continued from vol. iii. p. 375). — The Secretary read a 

 communication from M. Geoffroy-Saint-Hilaire, entitled " New Ob- 

 servations on the Nature of the Abdominal Glands of Ornithorhyn- 

 chus," in which the author states it to be his purpose to reply to 

 the observations of Mr. Owen on that subject, contained in the Pro- 

 ceedings of the Society, under date of the 12th of March in the pre- 

 sent year*. 



" The question no longer regards merely the simple fact, whether, 

 decidedly and absolutely, the Monotremata are viviparous, or ovipa- 

 rous ; whether we should reason upon them according to the rules 

 of the past, and apply to them the entire character of Mammalia ; or 

 whether we are not compelled to see in them sufficient anomalies to 

 embrace them in views of progress. 



" Let us state the case more precisely. There is but one single 

 consideration to be discussed ; viz. whether the gland on each side 

 of the abdomen is mammary and lactiferous (as Mr. Owen thinks), 

 or whether it is not a gland of a different kind (as I, for my part, 

 believe). I call it a gland sui generis, and have lately proposed to 

 denominate it Monotrematic, as it attains its maximum of composi- 

 tion among the Monotremata. 



* See Lond. and Edinb. Phil. Mag., vol. iii. p. 0*4. 



