BRITISH TYROGLYPHJIUL 



appear to vary far more in different species than even 

 the penis itself does ; but very little is known of them, 

 the only figures and descriptions being those of Nalepa ; 

 which include three species, and my own now pub- 

 lished for the first time ; this is doubtless due to the 

 fact that no other investigator has, so far as I know, 

 really dissected or cut sections of the Tyroglyphidse ; 

 and without these processes the sclerites cannot be 

 properly seen. 



In GlycyphaguH platygaster the supporting sclerite of 

 the penis (PL B, fig. 6) is in form a little like a capital 

 letter A standing upright in the body, i. e. in a perpen- 

 dicular plane ; only the arms of the A are not quite 

 straight, but are bent toward one another a little in the 

 lower part ; they increase in thickness from top to base, 

 and the lower end of each arm is rounded. The top 

 of the A is truncated and the cross-bar is nearer the 

 top than it would be in the letter, and is somewhat 

 curved, being convex below. Between this bar and 

 the top of the A an open space is of course left, and 

 through this the ductus ejaculatorius passes ; the 

 expansible chamber (dec) formed by its distal portion 

 lying below the bar and falling into the open part of 

 the penis. A small chitinous bar with enlarged ends 

 (PI. B, fig. 7, and fig. 5, cb) lies transversely below the 

 ductus ejaculatorius a little further into the body than 

 the principal sclerite (fig. 6 and fig. 5, sp), and this 

 gives further support to the ductus ejaculatorius. 



In Hericia Robini the whole design of the supporting 

 sclerites is different (PL B, fig. 4). There are two 

 paired pieces in this species ; each is a triagular frame- 

 work of chitinous rods with a posterior prolongation of 

 the ventral rod, which is the base of the triangle ; to 

 this prolongation the erector muscles are attached, the 

 retractors being inserted into the upper point of the 

 triangle. 



Nalepa * says that the supporting sclerites are paired 

 in T. longior, but that they join at the anterior ends ; 

 * ' Abth. I,' p. 214. 



