Professor Grube, of Breslau, has published the description of the insects and acaridæ found during the travels of Middendorf in Siberia. These descriptions relate especially to the Philopteræ of birds, the Pediculinæ of the mammalia, a flea of the Mustela Siberica, and an acarus of the Lemmus. Quite recently, an American naturalist, Mr. Packard, who has undertaken the study of so many different subjects, has published in the “American Naturalist” the description, accompanied by an engraving, of the Menopon picicola, found on the Picoides Arcticus from the lower Geyser basin, Wyoming territory, also of the Goniodes Merriamanus, the Tetrao Richardsoni, and the Goniodes mephitidis, found on a Mephitis from Fire-Hole Basin, Wyoming territory; of the Nirmus buteonivorus, from a Buteo Swainsonii; and of Docophorus Syrnii, from Syrnium nebulosum.
A great number of these insects live between the feathers of birds, and can be more easily observed, since they detach themselves after the death of their host. They are easily found on the skins of birds prepared for museums. These ticks form a family under the name of Riciniæ, and this family is divided into two parts, the Liotheidæ and the Philopteridæ.
Among the many generic divisions, one of the most interesting has received the name of Trichodectes; it contains twenty species, one of which lives on the dog, another on the cat, another on the ox; in a word, we discover a distinct species on each of the domestic
mammals. It has been said that the phthiriasis of the cat is occasioned by the abundance of ricini. The trichodectes of the dog has lately attracted the especial notice of naturalists, and that from the following circumstances.
There is no tape-worm more common in the dog than the Tænia cucumerina. But whence comes it? How is it introduced? This had been an enigma for many years, at the time when I dissected some dogs infested with Tænia serrata, in the Museum of Natural History at Paris. Together with the Tænia serrata, the number and age of which I knew beforehand, since I had myself planted them, there were found in the intestines of one of the dogs some individuals of the Tænia cucumerina. My dogs had taken nothing but milk, and cysticerci pisiformes. Were there cysticerci of different kinds in the peritoneum of the rabbit? The veil is now withdrawn. We have just said that the dog harbours a tick known under the name of Trichodectes, and in this trichodectes lodges the Scolex, we might even say the larva of the Tænia cucumerina. Dogs, especially young ones, lick their hair continually, and it is by this operation that the young tænia is introduced. It is by a similar process that the horse introduces the eggs of the Œstrus which are hatched in its stomach.
Many of these ticks live abundantly in birds, and multiply rapidly. The Liothe pallidum lives on the cock, the Liothe stramineum on the turkey, the Philopterus falciformis on the peacock, the Philopterus claviformis on the pigeon. It is to be observed that every bird can nourish many different kinds. Fig. 2 represents the tick which infests the sea-eagle, called Pygarg.
Fig. 2.—Ricinus of the Pygarg.
Fishes harbour crustaceans instead of ticks, and their number is not less considerable than on mammals and birds. These crustaceans have perplexed naturalists more than once, because they could only regard them as parasites. They live on the produce of cutaneous secretions, and if they improve, as do the ticks, the cleanliness of their host, they are not less useful in a hygienic point of view, for they prevent the accumulation of cutaneous productions.