4 T. V. Ho I Hi SON. 



to any other members of the geuus. The two species, as species are recognised 

 no\v-a-days, are perfectly distinct, but it is a fair question to ask how is their 

 present position at the opposite ends of the earth to be accounted for ? 



As to the terms employed in the following work, some words of explanation 

 are necessary. 



Naturalists have not always used the same terminology, and Mr. L. J. Cole (6) 

 has recently tabulated the essential variations. As, however, the terms used by 

 any one naturalist have not been fully adopted, and others have been introduced, 

 a complete account of the terminology used here is given. 



The entire Body of a Pycuogouid is divisible into three regions the proboscis, 

 trunk, and abdomen and this without regard to any of the appendages. Where 

 the body only is alluded to, it is to be understood that both the trunk and abdomen 

 are taken together. Measurements are taken dorsally, unless otherwise specified, 

 except in the case of the appendages, which are generally measured from the side, 

 and the length of the trunk is usually taken to the base of the abdomen ; in exceptional 

 cases, where the abdomen is vertical or very short, the trunk may be measured to 

 the extremity of the posterior lateral processes, but this is so stated. Its width 

 is always across the longest of the lateral processes. 



The C'ephalon is regarded as that portion of the trunk which lies in front of 

 the first pair of lateral processes, and the so-called neck is the narrowest part, 

 sometimes elongated, between those processes and the more expanded distal portion. 



Segmentation is not regarded as perfect or complete unless the four segments 

 of the trunk and the abdomen are distinctly articulated. 



The first appendage of the trunk is the Cheliforus, also commonly known as 

 the mandible. A considerable amount of confusion has been, and is still likely to 

 be, caused by the fact that the chela has most frequently been regarded as a single 

 joint. Obviously it consists morphologically of two joints, and in order to avoid any 

 misapprehension as to the number of joints, this appendage has been described as 

 chelate, or otherwise, and the scape, a name given by Professor G. 0. Sars to the shaft 

 supporting the chela, has been recorded as one- or two-jointed, as the case might lie. 

 This method of dealing with the limb is suggested in order to avoid confusion as 

 to the number of joints it possesses. 



The second appendage is the Palp. 



The third appendage is the Oviger. This convenient name was given by 

 Mr. L. J. Cole to replace the more cumbrous term " ovigerous," or " false leg." In 

 these two appendages the various joints are numbered from the base, and not named. 



The remaining four or five pairs of appendages are Legs pure and simple ; with 

 the use of the word " oviger," the qualification " ambulatory " or " walking leg " 

 becomes quite unnecessary. The terms used for the individual joints are those 

 adopted by Professor G. O. Sars, viz., first, second and third coxa, femur, first and 

 second tibia, tarsus and propodus. 



