the Nervous System of the Crustacea. 335 



at this general conclusion, that the nervous system of the Crus- 

 tacea is originally composed of two chains of medullary nuclei 

 equal in number to that of the locomotory or other appendages, 

 and that all the modifications which are met with in it, whether 

 at different periods of incubation, or in the different species of 

 the series, depend for the greater part upon the more or less 

 complete approximation of these ganglia, an approximation 

 which takes place in two different directions, viz. longitudinally 

 and transversely *. — Annates des Sc. Nat., June 1830. 



Description of a Species of Salix J'ound in Braemar. By W. 

 Macgillivray, a. M. (Communicated by the Author.) 



Having visited, in the beginning of August 1830, the beauti- 

 ful circular valley or corry containing Loch Ceanndin, and form- 

 ing one of the two terminal branches of Glen-Callader, near 

 Castleton of Braemar, for the purpose of examining its geo- 

 logical phenomena, I happened to find, among the numerous al- 

 pine and other plants growing profusely among its cliffs, a small 

 willow, which, after mature deliberation, I venture to offer to 

 the consideration of botanists as a species distinct from any 

 hitherto received as indigenous to the British isles. Mr Macnab, 

 of the Edinburgh Botanic Garden, having been with me at the 

 time, I presume that the difficulty of finding an appropriate 

 name for this supposed species in any circumstance connected 

 with its organization, will authorize me to name it after him. 



SaUx MacnaUana. Leaves elliptico-lanceolate, seirate, veiny, glossy on 

 both sides ; young twigs downy ; catkins cylindrical, with lanceolate, hairy, 

 scales ; germens nearly sessile, awl-shaped, downy. 



A stout, erect, bushy shrub, from two to three feet high. Stem smooth, 

 brown ; branches spreading, greenish-red, smooth and glossy ; young twigs 

 green and downy. Stipules unequally ovato-lanceolate, smaU, downy. Leaves 

 elhptico-lanceolate (tapering nearly equally at both ends), acuminate, serrate, 

 rigid, brittle, veiny, glossy on both sides, deep green above, a little paler 

 (but not glaucous) beneath, with obhque parallel veins, which are rather j)romi- 

 nent beneath, and reticularly connected by the venules at right angles. The 



" jVI. llathke does not appear to have been acquainted with our researches 

 into the nervous system of the Crustacea, or with those of M. Serres, other- 

 wise he would probably have been struck with the similarity which exists 

 between his observations and ours, and would have made the general remarks 

 which his work lias suggested to us, and which we have just made. 



