10 WOOD, 



short blunt spine on each side of middle lobe ; metathorax 

 contracted behind, with a strong angle at its upper cor- 

 ners, its concavity without setee ; each node transverse, 

 with a sharp spine, curving backward on each side, those 

 on second node longest. Abdomen subcordate. Legs 

 short, stout, black ; tips of femora, tibiae, and final tarsal 

 joint testaceous, or yellowish horn-color. 



Wo7'ker minor. Length, 0.20 in. This has the tuber- 

 cles on occiput subobsolete, and the declivity behind less 

 abrupt ; the anterior angles of thorax nearly coincident, 

 with no transverse connection. 



II. On the Phalangem of the United States of America. 

 By Horatio C. Wood, Jr., M. D. 



[Communicated December 9, 1867.] 



Intkoduction. 



The Phalanges, or Opilionina, as they are sometimes 

 called, are a suborder of the Trachean Arachnids of the 

 same rank as the Pedipalpi of the Pulmonary Arachnids. 



The external skeleton, the tegument, contains chitiue, 

 as does indeed that of all the arachnids, remaining firm 

 although becomingtransparent, when the animal is soaked 

 in a solution of caustic potash. It is variously orna- 

 mented with tubercles or spines, and more rarely punc- 

 tated or excavated. Good specific characters can fre- 

 quently be drawn from it. 



The cephalothorax and abdomen are closely fused 

 together, although in most cases the line of separation is 

 more or less distinct. The cephalothorax is never, at least 

 in any species the author has seen, at all segmented : it is 

 generally smaller than the abdomen, but in the family 

 GonyleptidiB, it is expanded into a broad plate, entirely 

 overshadowing the very small abdomen. The latter is in 

 all the Phalangea? more or less distinctly segmented. 



Near the centre of the cephalothorax is a more or less 

 prominent abrupt elevation or large tubercle, upon which 

 the eyes are situated. This tubercle, or as I have called 



