418 Miscellaneous. 



l<Evi, nitidd, longittidinaliter s^ubstriatd, albidd, fasciis cinerescen- 

 tibus macuUsque fuscis ornatd ; labio calloso, antice uniplicato ; 

 labri margine incrassato, flexuoso, in medio producto. 

 Hab. Pliilippines. Mus. Cuming. 



5. AcicuLiNA MACULATA, A. Adams. A. testa turritd, Icevi, 

 nitidd, albd, maculis luteo-fuscis longitudinalibus ornatd, trans- 

 versim sulcatd, sulcis distaniibus ; labio calloso, antice producto ; 

 columelld uniplicatd ; labro exttis marginato, intus lirato. 



Hab. Banang, Sargassinau, isle of Luzon, muddy sand, low water 

 {H. C). Mus. Cuming. 



6. AcicuLiNA viTTATA, A. Adams. A. testd turritd, albidd, ni- 

 tidd, fascid transversd fused interruptd ornatd, transversim sul- 

 catd, longitudinaliter costatd; labio calloso; columelld bituber- 

 culatd, et antice valde uniplicatd ; labro extus varicoso, intus den- 

 tato -lirato. 



Hab. Ticao, coral sand, 6 fathoms {H. C). Mus. Cuming. 



MISCELLANEOUS. 



On the Nervures of Leaves and their Distribution. 

 By L. VON BucH. 



Fossil leaves can frequently only be studied in their form and 

 neuration. The nervures have unfortunately been little noticed 

 by botanists, as though they were of but Uttle importance, and the 

 laws which rule their numerous modifications have not yet been 

 traced. It is to be regretted that, even in the best figures, the cha- 

 racters of the neuration of the leaves are badly represented, and 

 sometimes even in contradiction to the laws of nature. This is the 

 case not only with fossil, but also with hving plants. I wish to draw 

 the attention of botanists to this subject, and shall confine myself to 

 some leaves of dicotyledonous plants which are readily procured for 

 examination. 



A leaf is an organ essential to the life of the plant. In its deve- 

 lopment it relinquishes the cylindrical form of the branches and twigs, 

 and extends itself into a flat plate, one surface of which is turned 

 tov.ards the earth and the other to the sky. On the lower surface 

 are the stomata which absorb carbonic acid from the air, decompose 

 it, and set oxygen at liberty. Now this part of the leaf could not be 

 developed, still less could it maintain itself in this extended condition, 

 without the strong network of nei-vures which are found beneath the 

 leaf. The number of these nervures is fixed for each leaf; even for 

 each species. If the leaf grows extraordinarily, new nervures do not 

 appear on this large surface ; the number of nervures was fixed even 

 in the closed bud. The irregularities iu number in the bud are con- 

 fined within such narrow hmits, that they are of no importance in 



