3^ 



REV. J. E. HULL ON 



1. Dorsal setcC of mandible 2 or more 

 Dorsal setae fewer (i oro)... 



2. Apex of palp broadly truncate, its setse unequal... 

 Apical setae of palp subequal 



3. Dorsal setee of mandible 2 ... 



,, ,, many 



4. Apical article of palp clavate short 



Terminal article of palp cylindrical 



5. Dorsal setEe of mandible both basal 



,, ,, basal and median 



6. Setae of art. 5 of palp all equal ... 



Apical seta: of art. 5 of palp long^er than the rest 



7. Articles iii and iv of palp equal in length 



,, ., unequal 



8. Dorsal setse of mandible more than 12 (about 20) 



II or 12 



73- 



Bdella longirostris, Herm. 

 Bdella hexophthahna, Geo. 



3 



2 



longirostris, 



calva. 



4 

 6 



vulgaris, 

 lignicola. 

 dccipiens. 



5 

 norvegica. 

 silvatica. 

 littoralis. 



7 

 pallipes. 



8 

 lacHstris. 

 capillafa. 



66, 67, 68. 



General and common. The bases of the sensilli (a 

 pair near the base of the mandibles, another just 

 in front of the line joining the eyes) are frequently 

 conspicuously red like the eyes, and being of the 

 same size, have been mistaken for eyes. 



74. Bdella vulgaris, Herm. 



66, 67, 68. 



I take the species of the Italian authors as the 

 standard, as their naming is not questioned and 

 definite details are available. I append a comparison 

 of measurements of the palp — i, oi vulgaris, accord- 

 ing to Canestrini ; 2, vi//gan's mihi, from the 

 Northumbrian coast; 3, dicipiens, Thor. (from the 

 original description). The numbers represent in 

 order the length of tlie articles, beginning from 

 the second, the length of the longer apical seta 

 being added. In each case article ii is taken as 

 the unit. 



