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Dr. Franz Low (Ver. k. k. zool.-botan. Gos. Wien, xxvi, 1876, 211) gives in 

 detail the natural history of Trioza abieticola, Forst., which he finds on Rhamniis 

 catharticus. The hibernated female lays her eggs in April or May, in batches, on 

 the under-side of the tender leaves ; above these, on the upper-side, small pustular 

 elevations in a short time appear, beneath which, in about eight or ten days, the 

 young are hatched, and for a time remain there sucking the leaf, but at each succes- 

 sive moult they remove to another part of the under-side, or rarely go the upper-side. 

 The leaves sufFer no other than the slight deformity consequent on laying the eggs, 

 the sucking of the young TriozcB causing no change in their appearance. Then 

 follows a description of the young form which Dr. Low says is without doubt 

 identical with that described by Schrank as Chermes rhamni, and he adopts this name 

 for the species. 



Thus, two very distinct species have been referred, by different authors, to the 

 Chermes rhamni of Schrank, and both on the ground of the early stage of the life 

 of the insect agreeing with Schrank's description. But, as Dr. Low says (op. cit., 

 p. 210), von Frauenfeld has overlooked the fact that Schrank states the body of his 

 insect is transparent, and that this is not the case with Tr. Walkeri ; and this makes 

 it 80 much the more probable that Dr. Low is right in claiming that his species, 

 which has this peculiarity, is the rhamni of Schrank. Yet absolute certainty is 

 wanting, because there is yet another species of PyslUdce, unknown to Dr. Low, 

 which lives on Rhamnus catharticus — Ps. rhamnicola, Scott (Trans. Eut. Soc, 1876, 

 p. 548, 10), — of which the larva is hitherto not observed, but which, when found, may 

 also agree with Schrank's too brief description. 



Forster (Yerh. Yer. Rheinl., v, 97, 5) does not allude to Schrank's species further 

 than by saying, under the description of Psylla alaterni (of which he received the 

 types from Mr. Haliday, with this MS. name, and thence surmised that they were 

 taken on Rhamnus alaternus), that he strongly doubts if it be the Chermes rhamni of 

 Schrank. Mr. Scott (Trans. Ent. Soc, 1876, p. 535) places Ps. alaterni, Forst., as 

 a synonym of Ps. hippophaes, Forst., yet, without questioning this conclusion, based 

 probably on a comparison of the so-called species, it is only when the larva that lives 

 on Hippophae rhamnoides, and that which lives on Rhamnus alaternus, are discovered, 

 and they and their economy are compared, that there wiU be absolute certainty of 

 their identity or difference, or that the possibility of one or other, as the case may 

 be, being Ch. rhamni, Schrank, can be determined. 



With all these considerations in view, it appears to me to be rather premature 

 to apply Schrank's specific name " rhamni " to any species, and that it is desirable it 

 should remain in abeyance at present ; or, better, that it should be dropped altogether. 

 — J. W. Douglas, Lee : January 15th, 1877. 



Melanism, cf'c, in Insects. — This interesting subject has been ably treated by 

 Mr. Birchall (p. 130 ante) on the Darwinian and climatic theories, and by Dr. Buchanan 

 White as to its possible meteorological cause (p. llS aH^e),but I am far more inclined 

 to believe in the suggestion of Mr. E. Fetherstonhaugh (p. 215 ante), that the change 

 is produced by a vivid impression of the color of the surrounding objects on the 

 female insects during the period of (generation, and a strong tendency to re-produce 

 in their progeny the same colors among which thev themselves have lived ; and, as 



