400 PROCEEDINGS OF THE ACADEMY OF [May, 



has described the structure of an organ very nearly as I have, but 

 since his drawing is much too small and fails to give most of the details 

 one cannot gain from it the proper conception of such a structure. 

 He shows only six sense cells, all of which are at the base of the hypo- 

 dermis just beneath the organ. Also he connects the nerve fibres 

 with the dilatations, but he fails to show how the other end of the 

 sense cells connects with the nerve of the leg. 



(c) Disposition in other Orders of Arachnids. 



In regard to the lyriform organs of other orders of arachnids which 

 have been studied by Gaubert and Hansen, a brief summary is neces- 

 sary in order to understand the development of these structures 

 throughout the class of Arachnida. Gaubert failed to find any organs 

 in the Scorpions and Solifugids, and he saw only a small portion of the 

 organs present in the Pedipalps, Pseudoscorpions and Phalangitis. 

 Hansen who examined more specimens and with greater care, found 

 the following in two species of different genera of the scorpions: 

 several isolated slits on the trochanter and femur of the legs and palps ; 

 numerous slits on the patella, tibia, and metatarsus of the legs. All 

 of these vary much in size and are irregularly scattered. Almost all 

 of these slits are parallel with the axis of the leg and the dilatation is 

 always at the proximal end. 



In short, Hansen has found the lyriform organs in one family, 

 Thelyphonidae, of the Pedipalps as follows: the legs and palps are 

 abundantly supplied with scattered slits and the only organ which 

 occurs is on the metatarsus and it is highly developed. The chelicera 

 have numerous slits; the cephalothoracic shield and sternum only a 

 few. while the dorsal and ventral sides of the abdomen have many. 

 In another family, Phrynidae, the legs besides having many slits also 

 have two organs on each trochanter. There are many slits oh the 

 chelicera, dorsal and ventral sides of the abdomen and only a few on 

 the cephalothoracic shield. 



According to Hansen and Sorensen (1904) lyriform organs are 

 completely wanting in the order Palpigradi. 



Among the Solifugids Hansen has found only five scattered slits 

 on the last and fifteen on the first joint of the chelicera. These are 

 very different in size and are irregularly scattered. He says: "Un- 

 doubtedly we have here lyriform organs in a somewhat modified 

 shape." 



For the Pseudoscorpions Hansen states that only a few isolated 

 slits are found on most of the joints in the legs and palps, while an 



