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IV. — A Further Contribution to the Knowledge of British 

 Oribatidse. (Part I.) By A. D. Michael, F.L.S., F.E.M.S. 

 (with the assistance of C. F. George, M.R.C.S.E.). 

 (Read litJi January, 1880.) 

 Plates III. and IV. 



In this Journal, some time since,* I related the results of my 

 collection of, and observations regarding, the British representatives 

 of this family of Acarina during the year 1878. Throughout the 



EXPLANATION OF PLATES III. AND IV. 

 Plate III. 



Fig. 1. — Leiosoma pahnicincta. Full-grown nymph, dorsal aspect, X about 55. 

 The central ellipse with the innermost set of scales attached to it is the larval 

 notogastral skin, the other rows of scales belong to the successive nymphal 

 skins. 



Fig. 2. — The same. Nymph nearly full grown, ventral aspect, x about 30. 

 «, scales of the preseut skin ; b, true edge of the body ; c, flattened expansion of 

 the margin of the abdomen ; d, arched central part of ditto, bearing, e, anal plates ; 

 /, plates which will be called the genital jjlates in the adult ; g, mouth organs. 



Fig. 3. — The same. One of the hairs or scales, a, edge of body ; b, brown 

 apophysis ; c, lateral points of ditto ; d, colourlehs dotted head of central point 

 of ditto ; e, membranous expansion with black nervures. 



Fig. 4. — The same. Perfect creature, x about 40. a, stigmatic hairs; 



b, interstigmatic ditto. 



Fig. 5. — The same. Mandible, x about 115. 



Fig. 6. — The same. Other mouth organs, x about 115. a, labium; 6, maxilla; 



c, palpus ; d, Ungula. 



Plate IV. 



Fig. 1. — Orihata quadricornuta, X about 100. a, upper and outer point (or 

 horn) of the tectum ; b, inner and lower ditto ; c, spine from centre of anterior 

 margin of each half of the tectum ; d, stigmatic hair ; e, interstigmatic hair (or 

 spine) ; /, thin chitinous protecting ridge or blade, standing nearly on edge, along 

 the side of the rostrum ; </, concave projections from cephalothorax forming a deep 

 cavity for the reception of each coxa of the first pair of legs ; A, wing-like expan- 

 sion of the abdomen protecting the second and third pairs of legs. 



Fig. 2. — The same. Nymph full grown, x about 115. 



Fig. 3. — The same. Hood of the rostrum (perfect creature), x about 300. 

 a, rounded hood showing the buccal cavity and labium through the transparency 

 of the chitine ; b, flat, depressed, horizontal ridge ; c, remarkable pectinated spine 

 proceeding from the hood. 



Fig. 4. — The same. Mandible (perfect creature), x about 250. 



Fig. 5. — The same. Other mouth organs (perfect creature), x about 500. 

 a, labium ; 6, maxilla ; c, palpus and attachment thereof to maxillary lip. 



Fig. 6. — Oribata sphagni, X about 165. a, wing-like expansion of abdomen 

 become almost abortive. 



Fig. 7. — The same. Nymph full grown, x about 170. 



Fig. 8. — The same. Mandible (perfect creature), x about 220. «, one of the 

 projections which form attachments for the great retractor muscles. 



"Fio. 9. — The same. Other mouth organs (perfect creature), x about 160 

 (letters as in No. 5). 



Fig. 10. — Tegeocranus lahyrinthicus. Young nymph (amplification depends on 



Vol. ii. (1879) p. 225. 



