MELANOXANTHUS SALIOIS. 21 



Prof. Eupert Jones, F.R.S., informs me that at 

 Sandhurst, and thereabouts, the turnips mostly escape 

 " ckibbing," but nearly all cabbage, brocoli, and such- 

 like crucifera3 are much affected. 



In Russia the disease is known by a word meaning 

 cabbage-hernia. * 



Genus VIII.~MELAN0XANTHUS,+ BucUon, 



Body elliptical, rather flat. Vertex flat between the 

 antenn93. 



Antennae short. The third joint double the length 

 of the fourth. The seventh equal to the sixth. Frontal 

 tubercles inconspicuous. 



Nectaries short and pear-shaped, with trumpet - 

 like mouths. Prothorax marked by two lateral teeth. 

 Abdomen oval. Legs strong and short. 



Tail inconspicuous or none. 



Wings moderately long. Stigmatic veins with their 

 apices reflected. 



Melanoxanthus SALIOIS, Linn. Plate XLII, figs. 4 — 6. 

 Aphis saliciSi Linn,, Kalt. 

 Apterous viviparous female. 



Inch. Millimetres. 



Size of body 0-150 X O'OSO 3-81 X 2-02. 



Length of antennte O'OSO 2-02. 



cornicles O'Olo 0*38. 



* Mr. Percival Wright has called attention to this subject in 

 ' Nature,' July, 1878, p. 279. In the ' Botanische Zeitung ' for May, 

 1875, there appears the ghort abstract of _ a paper in Russian by M. 

 Woronin, who has satisfactorily traced this disease to the destructive 

 agency of a parasitic vegetable having some affinities with Myxo- 

 mycetes, and called Plasmidiophora hrassico'. The spores of this plant 

 attach themselves to the delicate root-hairs of various Cruciferae, 

 penetrate into the cells, and destroy the tissue. The roots of the 

 turaip then lose all their starchy matter, and swell into the knobs 

 in question^ which become crowded with nvicleated spores. 



t From fxiXag, black ; 5av06c, yellow. It is not, however, intended to 



