1911.] NATURAL SCIENCES OF PHILADELPHIA. 399 



as lyriform organs. Gaubert (1890) described the disposition of the 

 lyriform organs and said that these structures were as characteristic 

 for arachnids as are the pectines for scorpions. He gave them the 

 appellation of "lyriform organs." In (1892) Gaubert worked on 

 several species and found the organs as follows: one on the coxa of 

 the legs and palps ; three on the trochanter; two on the femur ; three 

 on the patella; three on the tibia; one on the metatarsus; no organs 

 but occasionally isolated slits on the tarsus. He said that the four 

 pairs of legs have similar organs and the first four segments of the 

 palps have organs located like those of the legs. Therefore he was the 

 first to see organ No. 1 on the coxa, and he has seen all the organs 

 present on these appendages, but he failed to observe them elsewhere. 

 Hansen (1893) selected Epeira diademata Clerk d\ the same species 

 that Gaubert used, and searched for organs and slits which were over- 

 looked by the latter observer. Besides finding the thirteen organs 

 on each leg, some isolated slits, the organs on the palps, chelicera and 

 the slits on the sternum as pointed out by Gaubert, Hansen found 

 many isolated slits of various sizes irregularly distributed on the palps, 

 legs, chelicera, maxillae, labium, near the epigynum, on the spinnerets, 

 and on the cephalothoracic shield in much the same manner that I 

 have described. Thus he was the first to recognize the two organs 

 on the pedicle as lyriform organs and pointed out for the first time the 

 isolated slits near the epigynum, on the spinnerets, labium and cephalo- 

 thoracic shield. 



My more comprehensive study of these structures has enabled me 

 to find all those organs pointed out by my predecessors, besides those 

 compound organs occasionally on the fifth joint of the palp, on the 

 tarsus of the legs and compound and simple organs on the spinnerets 

 and in front of the epigynum. 



(b) Structure. 



Bertkau (1878, 1885) described an enlargement at the middle of the 

 slit covered by a fine membrane and connected with a nerve fibre. 

 Dahl described a vessel under the transverse slits of organ No. 13. 

 Schimkewitsch says a lyriform organ has a chitinous coat which may 

 be incomplete and has edges which separate the parallel slits. He 

 describes the nerve fibres passing to the organ and their connection 

 with the ganglia (sense cells), but he failed to see the union of the 

 latter with the nerve "pedieux." Wagner states that these organs 

 present at the exterior a very thin membrane which afterwards covers 

 the dilatations which are located at the middle of the slit. Gaubert 



