122 BRITISH TYROGLYPHlDjE. 



moveable piece at the bottom of each maxilla, and 

 which Laboulbene and Robin had considered to be 

 the homologues of labial palpi, is served by a single 

 muscle ; but it must be remembered that the maxillae 

 are fused to form the maxillary lip, and are probably 

 scarcely, if at all, functional. 



The musculation of the palpi is practically of the 

 same nature as that of the legs, but in miniature, and 

 of course as there is not any free joint corresponding 

 to the coxa, the muscles special to that joint are not 

 reproduced. 



The Dorso-ventral Muscles. 



These muscles (PL C, figs. 1, 2, 3, mdv) are often 

 some of the largest in the body ; they are always paired 

 muscles, and serve, of course, to approximate the dorsal 

 and ventral surfaces of the body ; they usually lie 

 wholly in the abdomen, arise from the interior surface 

 of the dorsal cuticle, and are inserted into the ventral 

 cuticle by means of tendons ; which are usually short 

 but strong. Sometimes the spot where these muscles 

 arise from the dorsal cuticle is strengthened by a 

 chitinous plate embedded in the skin, as in some of 

 those of Hericia Robini (PI. C, fig. 2). 



Nalepa says that in Gawpoglyplms numerous bundles 

 of dorso-ventral muscles pass between the depressor 

 muscles of the second and third legs, and converge on 

 each side of the body to a point above the epimeron of 

 the third leg. In Hericia Robini I find, on each side of 

 the body, a strong fasciculus of dorso-ventral muscles 

 passing between the anterior portion of the ventriculus 

 and the lateral wall of the abdomen, and converging 

 to a single powerful tendon which is inserted into the 

 ventral cuticle just anterior to the genital opening of 

 the female (PL C, fig. 1) ; another, of less numerous 

 muscle strands, lies between the colon and the lateral 

 body-wall (PL C, fig. 2). 



In G-lycyphagus platygaster a dorso-ventral muscle 



