P. A. Buxton 
117 
detect a division of the body into an anterior notothorax (nth), and a posterior 
notogaster (ng). The line which divides these parts of the body is slightly in 
front of the middle and runs across the ventral surface behind the tocostome; 
Fig. 2. S. scabiei var. equi, ventral surface of adult female. A 1, 2, anal setae; cap, capitulum; 
e I-e II, epimeres of legs; gop, genital operculum; L 1, 2, lateral setae; sc, scale; sp, spine; 
ts, tocostomal seta; V 1-4, ventral setae; I-IV, legs, x 220. 
but its position is so indefinite that I shall endeavour to avoid the use of the 
terms notothorax and notogaster as far as possible. In living specimens in an 
advanced stage of pregnancy, when the egg has come forward to the tocostome, 
