Oribatidae 



3 



Oribata piriformis. 



Mdb. ( 2 °°/,). 



organs are curved and blade-like, and bear teeth on their anterior edges; 

 they move horizontally and are highly developed in Hoploderma. The 

 maxillary -lip bears the Palpi, which are very mobile, Duges has called them 

 „ fusiform" ; the basal joint is usually the shortest and the second the longest. 

 In the Phthiracarinae there are only four joints, 

 apparently from the coalescence of the second and third. 



The Mandibles (Mdb.) are of two joints and 

 chelate, the moveable arm of the chela is articulated 

 below the prolonged and narrow anterior end of the 

 first joint, and moves perpendicularly. 



The posterior part of the Cephth. bears 

 two outfoldings of the dorsal cuticle, which when Tendm 

 well developed are large longitudinal blades usually 

 standing nearly on edge; but they may be horizontal 

 or nearly so ; or they may be mere thickened ridges, 

 or entirely absent; they are called the Lamellae 

 (Lam.): they vary greatly in size and form. The 

 two Lam. are frequently joined at or near their an- Fig 

 terior ends by a transverse blade or ridge also formed 

 by an out-folding of the dorsal cuticle which is called the Translamella 

 (Trlam.). When the Lam. continue anteriorly beyond the Trlam. their 

 lower edges are not joined to the dorsal cuticle, thus they form free points, 



Fsytg org 



which may be very long; these are called the 

 n,t& cusps of the Lamellae (C. lam.). The cusp 

 often exists although there is not any Trlam. The 

 cusp, or the Lam. itself if there be not any cusp, 

 mam. almost always bears at or near its anterior end 

 a hair, usually long, which is called the Lamellar 

 hair (Lam. hair). In species where there is not 

 any Lam. these Lam. hairs generally persist, arising 

 from that portion of the dorsal cuticle, which would 

 .be folded outward to form the anterior end of 

 the Lam., if it existed. The portion of the dorsal 

 Fig. 4. Oribata piriformis ( ,so „). surface of the Cephth. bounded by the Lam. laterally, 

 Cephth., dorsal and lateral surface, the Trlam. anteriorly, and the Abd. posteriorly, 



3 Mview. ig caUed the D 0rs0 . vertex- 



The „Tectum u of Nicolet, and of many subsequent authors following 

 him, is an imaginary organ which has not any existance in reality ; although 

 appearances are very deceptive in this respect ; a few sections will at once 

 convince any-one of the error. It was supposed to be a sort of chitinous 

 shelf springing from the hinder part of the Cephth. where it adjoins the 

 Abd. and over-hanging the whole or part of the Cephth., and either standing 

 quite free or anchylosed to its surface; and this shelf was supposed to 

 have upturned lateral edges called the „wings of the Tectum". In com- 

 paring the writings of these writers with this book, or with the creatures, it 

 must be remembered that where the Tectum is said to have wings these 

 wings are the Lam., and the Tectum is the dorsal surface of the Cephth. 

 itself, i. e. the Dorso-vertex, and the Trlam., when present. — Where the 

 Tectum is said to be without wings it represents the Lam., which in these 

 cases are usually large and horizontal. 



At or near each outer posterior corner of the Dorso-vertex ; and con- 

 sequently close to the Abd. a very short chitinous tube directed upward. 



