122 . REPORT— 1870. 



On the Desert Flora of North America. By Dr. C. C. Paeey. 



The desert-tracts in North America, Ijdng het-ween 32° and 40° north latitude, 

 comprise a series of interior basins shut in by mountain-barriers from the moist 

 oceanic currents. These desert-districts, while vaiTing somewhat in their physical 

 features, owing to diiierences of elevation or geological structure, are characterized 

 by an arid climate, scanty rains, and i^ide extremes of heat and cold, both annual 

 and diurnal. 



In the lowest depressions the local drainage is collected in the form of salt lakes 

 or wide saline flats, the surplus water being lost by evaporation. 



In the desert vegetation there is a marked distinction between the annual and 

 perennial plants, the former being of slight texture, evanescent, and rapidly matm-- 

 ing, the latter exhibiting scanty foliage, frequent spinescent branches, and large 

 tap-roots; the leaves are frequently coated with a copious resinous varnish, or 

 clotlied with a dense wooll}' tomentum, serving in either case to check growth. 



The list appended to this paper contained 188 species, of which Dicotyledons are 

 represented by 169 species, included in 48 natural orders and 144 genera. Mono- 

 cotyledons include 19 species, comprised in 4 natural orders and 10 genera. The 

 natural order Compositaj is represented by the largest number of species (44), 

 nearly one-fourth of the whole. Leguminosas, which includes most of the dwai'f 

 trees and larger shrubs, has 25 species. 



On an Ebalia new to the British list. By C. "W. Peach, A.L.S. 



The author stated that the Ebalia was dredged by ]Mr. Jeflreys ofl" Uust, Shet- 

 land, in 1804, and that it difiered from all the other British Ebalias kno-um to him, 

 and then described it as follows : — " The carapace is pale, with faint whitish-pink 

 blotches ; the slightly raised pink tubercles are surrounded by white rings, givhig 

 the carapace a mottled appearance. The first pair of legs are equal in length, short, 

 but very broad, the upper edges of the joints arched, with a sharp perfectly smooth 

 keel. The other feet are slender, faintly granulated, and, in addition, have on the 

 outer edges strong and long blunt spines ; the upper joints have each a single row 

 of C or 7, the two next generally two rows each ; the lowest joint pointed and 

 smooth. These spines on the smaller legs, \f\\h. the very peculiar form of the 

 larger ones, are so marked that he felt justified in naming it Ebalia spiuosa. Should 

 it have been found in the Scandinavian seas and described, this name must then be 

 considered only provisional." 



Notes on the Cuclcoo-Jloiver or Lachfs-Smoclc (Cardamine pratcnsis). 



By Jonx Price. 



The leaves are, unlike those of other cresses, strictly compound, each leaflet being 

 jointed, and very apt to drop ofl" without decay or fading. They then act as seeds, 

 producing one or more little plants, and, like seed-leaves proper, waste away as the 

 embiyo thrives. The terminal leaflet often gives birth to tour or five plants ; in 

 one instance nine, in another ten were formed. This also takes place, without de- 

 tachment or extra moisture, even in the linear leaves high up the flowering stem. 

 The joints of the short petioles sometimes germinate too after the leaflets have 

 fallen. From observations without lens ("by the aid of the naked eye," Archer) 

 the radicle appears first, as a white thread ou the upperside of the leaf, the plu- 

 uiide being at first enclosed in a green transparent vesicle, which bursts like an 

 egg. The first plant always jjprings from the depression at the jimction of the 

 leaflet -^-ith its petiole, and those on the midrib precede the others, none ever ap- 

 pearing, as in BryojihjUum, on the outer edge. With this exception, the whole of 

 the upper surface seems to bristle with life at ever)^ point, ready to break out under 

 favourable circumstances. The phenomena may be promoted, and easily observed, 

 by laying the leaves, in various postures, on wet blotting-paper, lint, moss, &c. in 

 a dish, which shoukl be frequently sprinkled -wdth water. A dried specimen of the 

 whole plant with many leaves germinating, ybi/zK? under the w,was exhibited*. 



* The author would be glad tO furnish experimenters with good subjects. Address u8 

 Watertrate Street, Chester. 



