DR. JOHNSTON ON THB ACARIDE8 OK BERWICKSHIRE. 299 



shield between the insertions of the two mid pairs of legs ; 

 and an anal tubercle with a minute dark speck in front of it : 

 lio8trum thick, triangulate, thickened at the base where the 

 palpi originate : Palpi pedifurm, longer than the Nostrum, 

 bristly, converging and bent downwards at the apex so as to 

 appear blunt, 6-jointed, the two basal joints thick, the others 

 tapered, the terminal small and very bristly, the penultimate 

 with a singular palmate or pectinate bristle at its inner arti- 

 culation with the terminal, and a moveable spine below it ; 

 on the inner side of the third joint there are two small cla- 

 vate processes : Legs 8, equally distanced in their origins, yel- 

 lowish-brown with pale joints, bristly, the first pair slenderer 

 and rather longer than the hinder pair, which again are rather 

 longer than the body, and fully a third longer than the inter- 

 mediate pairs ; these are nearly equal in length, but the se- 

 cond pair is the stoutest : the legs are all six-jointed, tapered, 

 1st joint short, 2d elongate, 3d shorter, 4th as long as the 

 second, 5th short and small, only slightly divided from the 

 6th, which is long and tapered, and continued into an abrupt- 

 ly slender pedicle, terminated with a large vesicle and a pair of 

 minute spreading claws : Bristles originating from a minute 

 bulb, setaceous, smooth ; those of the upper articulations are 

 shorter than the diameter of the joint and patent, those of 

 the lower considerably longer, pointing downwards ; those 

 from the distal end of the tarsal joint reaching almost to the 

 vesicle: Pricker arising from the coriaceous skin on the 

 shoulder, between the fore and hinder pairs of legs, from a 

 bulbous base on which it appears to be moveable ; it is straight 

 and not sharp pointed : The vesicle of the fore legs is much 

 more shortly pedunculated than the others, and the bristles 

 overtop it. 



The structure of the oval apparatus is complicated and dif- 

 ficult to describe, not because of the minuteness of the parts,* 

 for they are comparatively large, but because of the difficulty 

 of bringing them in one view under the microscope so as to 

 discover the relation of the respective parts to each other. 

 There is in the centre a triangular upper lip, consisting of two 

 pieces joined by a plain suture, and each pointed with a short 

 stylette. On each side of this lip we see a maxillary process 

 forked at the apex with two small claws ; and external to the 

 maxilloe, and probably coalite with them, two delicate organs 



• " est trop petite pour que nous puissons pan*cnir 4 bien distinguer 



les parties dont elle est compostfe." — Reaumur. 



