382 
THE ANATOMY OF ARGAS PERSICUS 
(OKEN 1818). 
PART III 1 . 
By L. E. ROBINSON, A.R.C.Sc. Bond., 
and J. DAVIDSON, M.Sc. Liverpool. 
{From the Cooper Laboratory for Economic Research, Watforcl.) 
(With Plates XXV to XXVIII and 8 Text-figures.) 
The Muscular System. 
Plate XXV (see also Part II, Plates XV and XVI). 
The muscular system is so highly developed in the Ixodoidea, that 
it is no matter of surprise that it has been the subject of more or less 
detailed treatment in most of the publications dealing with tick 
anatomy ; but, with a single exception, the existing descriptions do not 
extend beyond a general classification of the various muscles, with the 
addition of brief remarks, in some instances, on the histological structure 
of the muscle fibres. In the majority of cases, also, the observations 
only apply to the Ixodid ticks, and although the general arrangement 
of the musculature in the two families of the Ixodoidea is not funda¬ 
mentally different, the comparative anatomy of the muscles offei’s some 
difficulty, owing to the great morphological differences which the two 
families present. 
So long ago as 1858, Heller 2 , in his extensive work on the anatomy 
of Argas persicus, observed that the dorso-ventral body muscles present 
certain differences to the muscles of the appendages, and that the muscles 
1 Parts I and II appeared in Nos. 1 and 2 of this volume; pp. 20-48 and pp. 217-256, 
respectively. 
2 Heller, C. (1858), p. 803. 
