The late Professor L. Agassiz, in 1867, requested of me a detailed plan for the development of the entomological department of the Museum, Among the different collections proposed was a biological collection similar to my own for Neuroptera and Pseudo-neuroptera, but extended to include all Arthropoda. The Professor in a marginal note stated that this collection should be commenced immediately, and developed as rapidly as possible. In my collection the alcoholic objects were included in vials placed horizontally near the pinned dry objects, so that all belonging to one species were together and presented a clear view to the observer. I used vials closed with cork stoppers, which for a small collection and by a continual supervision, proved sufficiently safe. Nevertheless experiments were made with several substances, hoping to prevent the evaporation of the alcohol and the necessity of refilling a large number of vials every six months.

The Acarina, especially the more minute forms, have been but little studied in America, a fact which seems the more strange when we consider what interesting objects they form for microscopic work. As in most groups of Arthropoda, the pioneer work in this country was done by Thomas Say, whose descriptions of a number of the larger species appeared as early as 1821. Later on Dana and Whelpley (1836), and Haldeman (1842), contributed descriptions of a few species. More recently Dr's. Fitch, Leidy, Packard, Riley, LeBaron and Shimer, and Mr. Ashmead, have published descriptions of species and notes on habits, while quite lately Mr. Harry Garman has published a valuable paper on the Phytoptidæ, which it is hoped he will follow up by still more extensive study of this family.

In the Oct. number of this journal I noticed with interest the article by Mr. Clarkson on Elaphidion villosum, Fabr. I have reason to believe that the same is partly the case also with E. parallelum, Newm., which I find to be the common oak-pruner here. But I do not agree that it is always, or even in the majority of instances, the case with either species.

2. On the scarcity of certain Species in 1885.

The most notable instance was that of C. Philodice, which is usually a very common species here. Throughout the year I saw but three or four examples.

In 1884, V. Cardui was remarkably abundant, as it seems to have been all over the Northern States. But in 1885 I scarcely saw one.

Among a very interesting collection of Mexican and other Hemiptera sent to me by Mr. Samuel Henshaw, Curator of Boston Society of Natural History, for identification, I find two species new to science and peculiar to genera never before detected in North America, although both are well represented in the European fauna.

In the first genus, Stenocephalus A. & S., in Europe, four species are known, principally peculiar to the southern portions of that continent.