156 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



cauda and may perhaps have been passed over for that 

 species, but it can be readily distinguished from it by the 

 much shorter caudal stylets and also by the shape of the 

 fifth pair of feet. 



Ascomyzon thompsoni, n. sp. PI. V., figs. 16 — 26. 



Description of the species. — Female. Length 1 millim. 

 O^gth of an inch). Body broad, suborbicular in shape, 

 cephalothorax broadly ovate, last segment of thorax and 

 abdomen much narrower, rostrum not prominent. An- 

 tennules slender, twenty-one-jointed, the first being the 

 largest and ciliated on its upper margin ; second to 

 eighth joints small and of about equal length, ninth joint 

 smaller than any of the others, eighteenth joint furnished 

 with a short sensory filament. The proportional lengths 

 of the joints are shown in the following formula : — 

 48.7.7.5.6.6.6.7.8.4. 7 .8.11.8.12.11.14.15.7. 8.7 

 12 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 



Antennae four-jointed, first joint long and bearing near 

 the distal end of the lower margin, a small one- jointed 

 secondary branch, which bears at the apex a moderately 

 long seta, a small hair also springs from near the middle 

 of the upper margin; second joint of the antennas shorter 

 and narrower than the first and having its lower margin 

 ciliated, third joint very small, fourth joint about as 

 long as broad and bearing at its apex one strong curved 

 spine and two setae. Mandibles slender, and stylet shaped ; 

 palp elongate narrow, two-jointed, second joint about one- 

 third the length of the first and bearing at its apex, one 

 long and one short plumose seta. The maxillae consist 

 of a short basal joint bearing two lobes of about equal 

 length, but one is considerably narrower than the other, 

 each lobe is furnished with four plumose setae ; one of the 

 setae on the broad lobe is much stouter and longer than 

 the others, two of the other setae on the same lobe are 



