124 Antennce, Mandibles and mandihidar Palps in Ricimdei 



of the surface where it terminates; besides some hairs are fouDcl along the distal part of 

 the outer margin. The function of these hairs is no doubt to intercept the blood of the 

 prey when this has been cut to pieces. Hairs serving this purpose, frequently collected into 

 clusters or brushes, are of frequent occurrence in Arachnida, armed with powerful cutting or 

 clipping antennse. such as Scorpiones, and in a still higher degree Pedipalpi. 



The second joint is curved like a sickle, particularly in Gryptocelliift. Its transversal 

 section is nearly triangular. In Cryptostemma the ventral surface is only slightly sharpened 

 into the cutting edge, whilst that side of the joint which is opposite the process of the first 

 joint is excavated longitudinally and more prominent towards the ventral surface (PI. IX., 

 fig. 1 c). In Cryptocdlus Simonis (PL IX., fig. 3 d) the transversal section of the joint is 

 somewhat different, as it is broader, and at the same time thicker along the convex side, 

 and the edge is sharper because the slant which forms the edge and which is seen on the 

 dorsal surface commences a little in.side the convex side. The edge is sometimes sharply 

 serrate, but is also found merely to a greater or less extent crenulate. The articulation 

 between the joints is very strong. 



2. The second pair of Limbs or Mandibles (maxillae auctt.) and their Palpi (PI. VII., 

 figs. 1 b and 1 k — 1 n). In Rieinulei the basal joints of these appendices are united to each 

 other, as in Uropygi, but to a much greater extent than in these latter, whilst in all other 

 Arachnida, apart from Acari, they are free. In Uropygi the mandibles are coalesced in the 

 middle line, but in Rieinulei they fuse almost entirely ; a groove-like structure is, indeed, 

 visible on the lower ' surface of their uncovered part (PI. VII., fig. 1 6), but on that portion 

 of their lower surface which is covered by the second pair of coxae (PI. VII., fig. 1 k), and 

 on the upper surface (PI. VII., fig. 1 m) no vestige of a suture is visible. The mandibles 

 of Rieinulei exhibit this further difference from those in Uropygi, that they are destitute of 

 any anteriorly projecting part, such as is found in all Pedipalpi, though otherwise Uropygi 

 differ much from Amblypygi in the structure of the mouth. It will be convenient to postpone 

 the more detailed description of the mandibles until we have considered the structure of 

 the mouth in general ; but we may remark in this place that they cannot be moved 

 independently of each other, but onlj- together, and that the distinction between a pars 

 manducatoria and a pars palpigera, which is observable in most Arachnida, does not exist 

 in Rieinulei. 



The Palpi (PL VII., figs, lb, p, and lo; several figures on PL VIII. and IX.) present 

 a structure which is quite unique amongst Arachnida. They consist of two trochantei'ial parts, 

 one femoral, one tibial, and one extremely small tarsal jDart. The first trochanterial part 

 of the palpus is short, almost pjTiform, and admits of no movement relatively to the mandible 

 ■except upwards-outwards and downwards-inwards, but this movement is not performed in 

 a straight, but in a rather arched line. The second trochanterial part is somewhat compressed, 

 the posterior (lower) portion being expanded, and it can be moved relatively to the first 

 trochanterial part in a somewhat slanting direction forwards and backwards ; when it is 

 ■extended backwards as far as possible the corner of the posterior expansion touches the 

 first trochanterial part. When viewed from the outside the transversal line of contact between 

 the second trochanterial and the femoral parts is quite straight, and the connecting membrane 

 is not visible from the outside ; the relative movement between these two parts consists in a 

 rotating movement of the femoral part round its own longitudinal axis to the extent of nearly 

 180° — a feature of which we know no other example in Ai-achnida or indeed Condylopoda of 



