A. D. MICHAEL ON A SPECIES OF GAMASU8. 261 



that I was led to reconsider my intention of abandoning this 

 paper. 



The species is a large and handsome one ; indeed, the largest 

 and most powerful Gamasus that I am acquainted with, and its 

 dorsal plates are divided into small parts, by fine sutures or 

 markings, looking like the scales of a fish, which is also the 

 case with Kramer's species. The form and structure of the 

 second pair of legs in the male is also very remarkable, but here 

 again it resembles Kramer's species. There are, however, 

 numerous more or less important differences from that species ; 

 those which have merely a value as distinguishing species I 

 shall leave for the description at the end of this paper, and 

 shall only mention here those which seem to have a wider 

 interest or to be otherwise remarkable. 



What struck me first was the form of the so-called oral tube. 

 In Gamasids in the median line of the anterior edge of the body, 

 and lying below the dorsal plate and above the ventral there is 

 a short, wide, chitinous tube (the oral tube), PI. xvi, Fig. 12. 

 This tube can be nearly retracted within the body, or almost 

 entirely exerted. It is formed below by the maxillary lip, 

 with its parts corresponding to the galea? of insects, &c, and 

 with the maxillary palpi attached ; and above it is formed of 

 what may be considered as equivalent to a labrum or epistome. 

 Through the hollow of the tube (lumen) the protractile man- 

 dibles (chelae) are protruded ; or darted would give a better idea 

 of the motion, and the lingula, &c, are within the tube. The epis- 

 tome is variously shaped in different species, and is often of 

 very quaint pattern. The mandibles also vary greatly, although 

 always chelate in the true Gamasids. This variety of the man- 

 dible is chiefly in the male sex, and modern writers upon the 

 group have distinguished species chiefly by the form of these 

 two parts, and in most of their writings these are the only parts 

 figured. It has been fully recognised that the mandibles of the 

 males and females commonly differ, and only those of the 

 male are usually drawn, as there is not much variety in those of 

 the female, but I am not aware that any one has ever remarked 

 any sexual difference in the form of the oral tube, and the 

 epistomal portion of it is iisually figured for the identification 

 of species without mentioning which sex it belongs to. In the 

 present species, however, I found to my surprise that the 



