288 DR. THISELTON DYER. 



finger-tips, having here and there slender hairs. The last 

 joint of each of the light yellowish-brown iimbs is the 

 longest, and the claws are recurved, as in the sketch. The 

 posterior third of the body has a dentated border, with 

 eleven square-edged lobes. The intervals between these are 

 marked on the surface by deep grooves, from which the 

 surface ridges radiate. 



Just in front of the first of these sulci, on each side are 

 two subpyriform glandular bodies filled with globular, 

 highly refracting cells. This sac has thick, uniform walls, 

 and opens on the margin of the body at 6, Plate XIV. 

 A still more highly magnified view of this body is shown at 

 fig. 3. I have not seen any organ like this in any other allied 

 form. 



The line separating the thorax from the abdomen is very 

 faint. The compressed, scale-like shape of the body is well 

 fitted to prevent the animal from being fatally squeezed 

 between the imbricating plates of the host's defensive 

 armour. 



Note on the Imbedding of Crystals in the Walls of 

 Plant-cells. By W. T. Thiselton Dyer, B.A., B.Sc. 

 F.L.S. (With Plate XIV, figs. 1—4.) 



In describing in the January number of this Journal the 

 occurrence of strings of crystal-bearing cells on the outside of 

 the fibro-vascular bundles of the Screw Pine, I remarked 

 that the thickened walls of the cells almost adhere to the 

 contained crystals. I believe the explanation of this circum- 

 stance is supplied by a paper published by Dr. E. Pfitzer 

 during last March in the seventh, eighth, and ninth numbers 

 of ' Flora.' Count Solms had pointed out in the ' Botanische 

 Zeitung,' in 1871, that crystals of calcium oxalate are formed 

 within the actual substance of the cell-wall itself. His 

 observations were made upon Conifers, and Dr. Pfitzer, in his 

 paper, describes a similar occurrence in the leaf-parenchyma 

 of some species of Drac(Bna. But in the case of Citrus 

 vulgaris, where crystals occur apparently more or less com- 

 pletely imbedded in the cell- wall. Dr. Pfitzer has shown that 

 the history of their formation is different. They originate, 

 in fact, free from any attachment, in the middle of the proto- 

 plasmic cell-contents (fig. 1). Subsequently they appear, 

 still without contracting any adhesion, to receive a coating of 



