PYCNOGONIDS 255 



remainder of the surface as the ' sole.' In describing the joints 

 of the palpi and ovigera the abbreviations/. I, /. 2, etc., are often 

 used, and similarly the joints of the legs are abbreviated to c, I, 

 r.2, c.$ for the first, second, and third coxal joints,/, for femoral, 

 etc., when the meaning cannot be mistaken. In speaking of the 

 dimensions of a joint, ' length ' is always in the direction of the 

 axis of the appendage, ' breadth ' at right angles to it, regardless 

 of the proportions of the two. The same rule also holds true for 

 the parts of the body, ' length ' being in the direction of the axis 

 of the animal; but when the lateral process alone is spoken of, 

 it has the same long axis as the leg. In general, proportionate 

 measurements are used in preference to absolute, as it is thought 

 they will prove more practicable in determining species. Measure- 

 ments of the length of the whole animal, or 'body,' as it is usually 

 called, are taken from the tip of the proboscis to the tip of the 

 caudal segment. When possible the specimen is flattened out so 

 that the proboscis projects straight forward and the caudal seg- 

 ment straight backward in order to get this measurement, and 

 when this is not possible it is approximated as nearly as can be. 

 Extent is another measurement which it is difficult to obtain with 

 any degree of accuracy. When practicable I have done this by ex- 

 tending the specimen as fully as possible and measuring directly 

 usually from the tip of the second leg of one side to the tip of 

 the third leg of the other. For one reason or another this can 

 not always be done conveniently, and in such cases it is often 

 necessary to get the leg measurement joint by joint, and to deter- 

 mine the total extent approximately in this way. Such a degree 

 of accuracy is generally not necessary in determining the abso- 

 lute size of the species, but is often of much importance in order 

 to get proportion of extent to length, and to other dimensions, 

 in the same specimen. Most authors give measurements for 

 at least length and extent, but as they seldom state just 

 how they are made, they can be used only with considerable 

 caution. 



The following comparative table of terms used by several of 

 the more recent authors may be of service in comparing descrip- 

 tions. A much more complete synonymy will be found in Mei- 

 nert's report ('99). 



