4 Mr. R. I. Pocock on the 



ScMzonotus presents a strong general likeness to Thely- 

 phomis in the form of the body, structure of limbs, &c. The 

 telson, however, consists of a single short segment, and the 

 carapace being rather shorter, has left a larger space between 

 its hinder border and the first abdominal tergite ; but this 

 area, otherwise unprotected, is covered by a single or a paired 

 sclerite, which may be either a special development or one of 

 the original ceplialothoracic tergites. In any case tlie result 

 of this segmentation of the carapace is the power to flex the 

 two posterior somites in a vertical plane, the joint being 

 situated between the fourth and fifth appendages. There 

 appears usually to be a single pair of respiratory stigmata 

 situated behind the first sternite, as in Thelyphonus. The 

 posterior pair that are developed in Thelyphojius appear to be 

 functionless, but upon the third, fourth, and fifth sterna 

 (morphologically the fourth, fifth, and sixth) close to the 

 posterior margin and behind the muscular impressions a pair 

 of dusky patches are visible. These appear to be some 

 internal organs seen through the semitransparent cuticle, and 

 I believe they are the homologues of the three posterior pair 

 of lung-sacs of the Scorpion *. In one species described by 

 Dr. Thorell — 8. Camhridgn — two eyes are present ; but 

 most interesting of all is the disappearance of the respiratory 

 stigmata and the fusion "f of the first two sterna of the abdo- 

 men, which leaves only ten for this region. This species is 

 of interest in connexion with the possible derivation of the 

 Solifugw from this group. 



The third group of Pedipalpi — the Phrynidge — are of 

 interest inasmuch as in all the characters that they depart 

 trom the Thelyphonidse they approach the true Spiders or 

 Aranece. The whole body is very much shorter than in the 



operciila iu tlie JMygalomorphte, while the posterior lung-sacs belong to a 

 somite whicli lias no free sternite. This view is entirely opposed to 

 Macleod's liypothesis respecting the derivation of the lung-books of the 

 spiders. 



* These structures have not, I believe, been previously noticed, but 

 they are certainly visible in both the specimens of this genus that I have 

 seen. For affording me an opportunity to examine these examples I am 

 indebted to the kindness of the Rev. O. P. Cambridge, who with great 

 liberality sent to me the types of the two species he has described. That 

 named tenuicmuhta is referable to the so-called genus 2'ripeltis of 

 Thorell, having the posterior cephalothoracic tergite paired. 



t Dr. Thorell's words describing this feature are "... nee limitem inter 

 scuta ventralia \m et 2m, nee sjnracula certo discernere potui^'' (Ann. 

 Mus. Genov. xxvii. p. 560, 1889). This author ascribes only eleven terga 

 to the abdomen. I cannot but think, however, that he overlooked the 

 first small tergite, which is present in the two specimens seen by me. 



