JOURNAL OF MICROSCOPICAL SCIENCE. 



DESCRIPTION OF PLATE VIIL, 

 Illustrating Mr. Hepworth's paper on the Mandibles of Acaridae. 



Fig. 



1. — A portion of human skin, including an itch pustule ; 48 diameters. 



a, ova of Acarus Scahiei. 



b, young insects. 



c, effete matter deposited by insects. 



2. — Full-grown insect, Acarus Scahiei ; 65 diameters. 



3.— Mandible of ditto ; 390 diameters. 



4. — ,, of Acarus Sacchari (female) ; 390 diameters. 



5. — ,, of „ (male) ; 390 diameters. 



6. — ,, of Acarus of domestic Fly ; 630 diameters. 



7.* — ,, of Long-legged Spider ; 30 diameters. 



8. — „ of Acarus of Blue Beetle and Humble Bee. 



G.f — „ of Cheese Mite ; 390 diameters. 

 10. — ,, of CJielifer cancroides ; 65 diameters. 

 11a. — ,, of parasite of Mole ; 240 diameters. 



b, proboscis ; 240 diameters. 

 12. — „ of another parasite of Mole ; 240 diameters. 

 13. — ,, of parasite of Babbit ; 240 diameters. 

 14. — Mandibles of parasite of Water Eat ; 200 diameters. 



* Perhaps, instead of calling these mandibles, they would more properly come 

 under the term maxillary palpi ; as in the Scoi'pion. It appears to be one of the 

 non-spinning Arachnidans. If a leg get accidentally torn off, there is a spasmodic 

 twitching, which continues some seconds in the severed limb. This is so familiar 

 a phenomenon that there will be little difficulty in recognising the kind of spider I 

 mean. As I am an inquirer, I shall be glad to see any remarks on the subject. 



t Rymer Jones says (R J.'s 'Animal Kingdom,' p. 308), in speaking of the 

 Acaridcp, " The mouth seems adapted for suction, and the jaws form a piercing 

 instrument, barbed at the extremity." Note. — I have not been able to detect this 

 piercing instrument : it has two powerful mandibles, as seen above, and equally 

 powerful maxilla" ; and in action they indicate too much motion, and which is of a 

 different character to that where suction is accomplished. How could a flour mite 

 (which has precisely the same kind of apparatus) subsist on dry flour, if it had organs 

 adapted to suction only ? I can easily conceive how the parasite of the Mole (fig. 11 ), 

 with its barbed proboscis, could live by suction. 



