HANSEN AND SÖRENSEX, THE TARTARIDES. 37 



fourth order, Ricinulei, is increasecl from three to eight. The 

 contents of the present treatise preaches the same; zoologists 

 and collectors ha ve on the whole neglected these most interesting 

 groups of rather small Arthropoda. 



On 3Iejisiireiiients, Drawings and Terniinology. — The length 

 of the body (flagellum omitted) and of the first pair of legs has 

 been measured with compasses. The figures of the first leg 

 together with the mandibular palp and of the fourth leg of male 

 and adult female of the same species ha ve always been drawn 

 tviih the same degree of enlargement — but it was of course 

 necessary to draw these parts of large species with a Jower 

 degree than those of smal) species — the length of the first 

 leg being measured, the absolute length of the palp and of 

 the fourth leg has been calculated by means of the drawings. 

 This mode of proceeding rendered it possible to give the ac- 

 curate length of the palp and the fourth leg without any risk 

 of damaging the specimens. In all these measurements the 

 trochanter has been included, while the coxa is always omitted. 

 In the descriptions the relative dimensions of severa] joints 

 or set of joints in the same appendage ha ve been given: the 

 animal was laid on the object-glass in glycerine diluted with 

 water, the appendages in question were arranged so horizon- 

 tally as possible in order to avoid errors in the measurements, 

 and these were taken by the ocular micr ometer, so fchat the 

 numbers read off could be divided. While the real length or 

 depth of the joints in question is not worth recording, the 

 relative measurements, the proportions, are often very impor- 

 tant; it may be emphasized that especiaUy the relative dimen- 

 sions of parts of the foot of the first })air of legs are in tyiany 

 cases absolutely necessary for the determination of the adnlt females. 

 Measurement by the eye of such parts ifi quite insufficient; 

 it is absolutely necessary to apply the method described, if 

 the student w^ill arrive a t trust wort hy results. Fu^thermore 

 I may point out as to the foot mentioned that among the 

 numerous relative dimensions those used by me have been se- 

 lected as the most serviceable; the relative length or depth 

 of the five proxima] tarsal joints has been omitted as nearly 

 valueless, presenting too small differences between most species. 

 Not only immature specimens but even the adult females of 

 the major part of the species are so closely similar not only in 

 general aspect but in nearly all features, that if the precautionar^^ 



