160 Miscellaneous. 



sion of its cells, by which means the epidermis itself ceases to exist 

 as such. 



Consequently the outermost layer of cells on the surface (of a 

 root-envelope consisting of several layers of cells) is not the epidermis, 

 but is to be regarded, from its mode of production, as equivalent 

 to all the other layers. The cells of this layer may grow out into 

 radical hairs in all plants, but these are frequently produced only 

 when the roots adhere to foreign bodies. The hairs are often rami- 

 fied and variously thickened, and may be unrolled, in many plants, 

 in spiral bauds. 



In every root-envelope many cells are perforated when old. This 

 may be proved anatomically in many cases, and may always be de- 

 monstrated by injection with insoluble colouring-matters. 



The layer of cells situated beneath the root-envelope, and called 

 the " endodermis " by Oudemans, cannot, in accordance with its 

 developmental history, be regarded as epidermis. Fissure-like ori- 

 fices are never seen in it ; and when such have been supposed to be 

 seen, this depends upon an illusion produced by the section. The 

 endodermis is present in the aerial roots of all Orchideae, and never 

 lies on the surface. It always consists of two kinds of cells — namely, 

 elongated cells the outer walls of which at least are thickened, and 

 shorter cells which are always thin-walled. The latter always have 

 a remarkably large nucleus ; the walls of the cells of the root-enve- 

 lope adjacent to them are usually thickened in a different manner 

 from those which cover the elongated cells of the endodermis. When 

 the root-envelopes consist of but few series of cells, there is over 

 these a group of variously formed cells which may be described as 

 covering-cells (Beckzellen). 



The cortical parenchyma, the thickened ring, and the medulla 

 present peculiarities in the mode of thickening of their cells which 

 we do not meet with in the aerial roots of plants of other families. 



The aerial roots of many Aroidese likewise possess a root-envelope 

 agreeing precisely, both in structure and development, with that 

 occurring in the Orchidese. The aerial roots of the Cactese, on the 

 contrary, are destitute of a root-envelope. — Bericht der Akad. der 

 Wiss. su Wien, May 12, 1864, p. 87. 



Description of a new Mustek //•o?rt Quito. 



By Dr. J. E. GuAy, F.R.S. &c. 



Mr. Gould has transferred to the British Museum the skin of a 



small Mustela, received from Quito, which is very distinct from any 



we have previously seen. It is about the size of the European Weasel. 



Mustela aureoventris. 



Dark brown ; chin and side of the throat white ; throat, chest, 

 mside of fore legs, and belly golden yellow ; whiskers black ; tail 

 rather tapermg, as long as the body ; the soles of the hind feet hairy ; 

 the pad of the toes bald, callous, hairy on the sides ; ears rounded, 

 hairy. Length of body and head 6 inches, of tail 4^ inches. 



Hab. Ecuador.— Proc. Zool. Soc. Feb. 9, 1864. 



