INTERNAL ANATOMY. 71 



draw it so for T. siro, but Gudden's process of obtaining 

 it had evidently so washed and softened the organ that 

 its form Avas destroyed, for he does not draw, and 

 apparently did not suspect, any distinction between 

 the ventriculus and colon, but treats the two as one 

 long sack (see PL A, fig. 4). Haller,* speaking of 

 what he calls Tyroglyphus seliferus, a species which 

 Berlese f considers to be only a synonym of T. longior, 

 also omits to observe that the ventriculus and colon 

 are different divisions of the canal ; but he says that 

 the ventriculus is deeply constricted in the middle and 

 forms two retort- shaped halves ; of course the anterior 

 of these only is the true ventriculus. 



Seen from the side the ventriculus in all species of 

 Tyrogiyphidse with known anatomy widens towards 

 the posterior end, so that it is both broader and thicker 

 there than anteriorly ; to such an extent is this 

 carried that in Hericia Eobini (PL A, fig. 1 ; PL C, 

 fig. 1, /;) it is nearly as triangular in lateral aspect as 

 in dorsal. Nalepa draws the organ in Oa/rpoglyphus 

 anonymus J as of similar shape, and Haller gives the 

 same form for that of what he calls Tyroglyphus 

 setiferus. 



The ventriculus in all investigated species of the 

 family has two casca, and two only, but these are large 

 (PL A, figs. 1, 2, cse). They arise from the lateral edges 

 of the ventriculus, one on each side, as paired organs ; 

 sometimes they have a slight tendency to be placed a 

 little toward the ventral surface ; they are so in Glycy- 

 pliagus platygaster, and Gudden draws them so in Tyro- 

 glyphus siro (PL A, fig. 4). On the other hand, Nalepa 

 figures those of T. longior as nearer the dorsal than the 

 ventral surface (PL C, fig. 3). The caaca vary in form, 

 and in the precise position on the edge of the ventriculus, 

 according to the species ; in Hericia Eobini they are 



* ' Zur Kenntniss der Tyroglyphen und Verwandten," in ' Zeit. wiss. 

 Zool.,' Bd. xxxiv (1880), p. 276, pi. x, fig. 2. 

 f ' A. M. S. Crypt./ p. 109. 

 J Nalepa, Abth. ii, Taf. iii, fig. 16. 



