MOEPHOLOQT 01" THE PEDIPALPI. 23 



except at two points, one on eacliside of the middle line, where it 

 runs forward into triangular processes. To the middle of the 

 front edge of this sclerite is attached a chitinous plate, which runs 

 forward forming the dorsal wall of the genital vestibule. The 

 dorso-ventral muscles from the third tergite are attached on each 

 side of this process. 



There is little doubt that the genital plate corresponds to 

 the genital plate of the Scorpion, and is an appendage ; and I 

 am inclined to consider the second sclerite as also an appendage. 

 If, as I have tried to show in the Scorpion * and as Macleod f 

 maintains in Spiders, the lung-books are derived from the ad- 

 hesion of abdominal appendages to the ventral surface, there 

 must have been an appendage here in the course of development, 

 and at a comparatively late stage in the development oi PhrynusX 

 this plate has quite a different appearance from the succeeding 

 segments. The inturned posterior margin also and the absence 

 of a dorso-ventral muscle inserted in the plate itself are sugges- 

 tive, though I would not attach too much weight to the muscle 

 as the points of insertion of such structures readily change. If 

 this plate is to be regarded as an appendage, the anterior chi- 

 tinous process to which the dorso-ventral muscle is attached 

 naturally suggests itself as the corresponding sternite. This 

 point also I would not lay much stress on until the development 

 of this region is better known. 



Internal Anatomy. 



The greater part of the cavity of the abdomen is occupied by 

 the enormous digestive gland — the so-called liver — which forms 

 a solid mass concealing at first sight everything except the heart 

 and a few muscles. 



The Tieart (PI. III. fig. 1) is about the same size from end to end 

 of the abdomen, disappearing at the posterior end beneath a conical 

 mass of muscle connected with the three caudal segments, and 

 anteriorly passing into the thorax, about halfway up which it 

 passes in among the folds of the stomach. Injection being im- 

 possible, no attempt was made to trace the further course of 

 either end of the heart. A meshwork of small vessels, consisting 

 of a pair of longitudinal Vessels at each side with a transverse 

 vessel in each somite, lies on the surface of the digestive gland, 

 and is probably part of the blood-system. 



* Zool. Anz. 1892. t Arch. Biol. vol. v. % ^'^^^ infra, p. 34. 



