Arachnida. 3917 



number of eggs upon the feathers at the back of the head, neck, and throat. On a 

 more careful inspection, I found that the ova were only deposited in this situation, 

 where the bird, from the great length of the bill, could not reach them. The eggs 

 amount to many thousands : they are placed chiefly at the base of the feathers ; 

 their numbers varying from twenty to fifty on each. Whether the hornbills generally 

 are affected with these parasites I am unable to say ; but in three living toucans (birds 

 which bear some resemblance to the hornbills) now at the Regent's Park Gardens, I 

 find no trace of these animals. As regards other birds, my experience does not enable 

 me to speak. The bill of the hornbill and of ihe toucan is so beautifully constructed, 

 that the smallest insect would be crushed by its well adjusted point ; but the claw, I ap- 

 prehend, would be of little service in this kind of warfare. Whether the mites instinc- 

 tively deposit their eggs in the situation named, is a question difficult to solve ; but 

 looking to the habits of some grades still lower in the scale of creation (the coral in- 

 sect, for example), I think it more than probable that the animal in question does pos- 

 sess this amount of instinct. On placing several of the feathers upon which the eggs 

 are deposited under a power of 40 diameters, I find that the mite has escaped from the 

 greater number, but in several the young Acarus may be distinctly seen through the 

 egg-shell, the exterior of which is composed of cells of a pentangular form. I found 

 several of the mites dead on various parts of the body, and although dry aud shrivel- 

 led, their forms are tolerably distinct under the microscope. They present most of the 

 characters of the Acaridae. The mandibles are large, their inner edges trenchant, and 

 their anterior extremities expanded and lobated ; the legs are eight in number, with 

 the tarsi of all terminating in a disk-like appendage. The body and legs are furnished 

 with spines, and the posterior part of the body is pointed. In some specimens the man- 

 dibles are much smaller, but the disk-like tarsal appendage in all is very distinct. I 

 have immersed some of these Acari in spirits of turpentine, and hope hereafter to be 

 able to describe them more accurately. I believe they have never before been noticed, 

 for on referring to the interesting papers, and drawings of the Acariens, by MM. Du- 

 ges, Dufour, and Gervais, in the ' Annales des Sciences Naturelles' for 1833, 1839, 

 and 1841, I find none that correspond with those depicted in the inclosed drawings, 

 which I exhibited at the Zoological Society. — Edwards Crisp, M.D.; 21, Parliament 

 Street, May 13, 1853. 



Note on the Abstinence of Spiders. — In the February number (Zool. 3766) there is an 

 account, by Mr. Pickard-Cambridge, of a spider which lived for upwards of eighteen 

 months in a stuffed bird's case, without obtaining any visible supply of food, and 

 even increased considerably in size during that period : and in the following number 

 of this journal (Zool. 3809), Mr. Bree remarks on this statement, that the animal must 

 have obtained food by some means, it being impossible that it could have increased in 

 size without sustenance. Like Mr. Bree, I was much pleased with Mr. Piekard- 

 Carabridge's account, and, had I not been prevented by other avocations, should have 

 offered a few remarks on this subject before, it evidently being one of much interest 

 both to the naturalist and the physiologist. With respect to the length of time that 

 Mr. Pickard-Cambridge's spider lived apparently without food, it has been long known 

 to arachnologists that many species of Araneidea will bear a very protracted abstinence 

 without any perceptible diminution of vital energy. Martin Lister, in his " Tractatus 

 de Araneis," contained in the ' Historia Animalium Angliae,' which he published in 

 1678, has the following passage: — "Aranei nihil recondunt, quod diu sine cibo 

 vivere possunt ; per hyemem vero ex toto abstinent, et ne victum quidem quaerunt ; " 



