A. D. MICHAEL ON THE ACARINA. 229 



showed that this was so, and that the whole structure was folded into 

 corrugations in both directions, so that it reminded me, more than 

 anything else, of a circular glass ridge and furrow roof, like the 

 transept of the Crystal Palace, only that it would be necessary to 

 fancy the individual panes of each ridge also set ridge and furrow 

 fashion, so that each main ridge would be composed of smaller 

 ridges running at right angles to the main one. It will be readily 

 understood that this structure would easily collapse and expand in 

 both directions without injury. It would, moreover, expand 

 unequally in any direction, and would always retain a certain amount 

 of elasticity. 



The oviduct, when excerted, but not extended by an egg, narrows 

 somewhat rapidly from the point of attachment of the chitinous 

 doors, and then continues for the greater part of its length as a tube 

 of tolerably even diameter, deeply and closely corrugated, until it 

 arrives at a sort of slight collar, from which radiates a circle of 

 single hairs ; the tube then narrows to a constriction, which is the 

 narrowest point, and from thence expands sharply to form a bell- 

 shaped termination with the edge cut into wide curved indentations, 

 from within which proceed three long cusps, which remind one of 

 the copulative organs in Diptera. The office of these cusps is to 

 clasp and direct the egg during deposition, each cusp bearing two 

 pairs of strong hairs on its outer surface. It appears to me that the 

 variations in shape and diameter in different parts of the oviduct are 

 chiefly due to the greater or less expansion of the corrugations above- 

 mentioned. 



The muscles, by means of which the whole apparatus is excerted 

 have been already well-figured by Nicolet. 



PLATE XIII. 



Figs. 1 to 3. Pro ctophyllo des glandarinus (X 150) (after Megnin and 



Kobin). 

 Fig. 1. Male. Posterior part, ventral aspect. 

 Fig. 2. Nubile female ,, ,, „ 



Fig. 3. Reproductive female „ „ 



3. 3rd pair of Legs. 



4. 4th pair. 



a. Epimeron. 



b. Coxa. 



c. Trochanter. 



d. Femur. 



e. 4th or shank joint. 



