Coxal glands of the Arachnids. 235 



is very nearly reached (photo 3), although in no specimen has an 

 actual outlet been observed, but the dip may be an indication that 

 there was primarily an outlet at this point as well as the persisting 

 outlet on the fifth appendage. From the disposition of the coxal 

 gland, opposite the bases of both the fifth and sixth appendages, it 

 seems quite possible that it has been formed from a coalescence of 

 the originally distinct organs of the two appendages. 



Bkauer (1894) in embryo scorpions observed the development 

 of nephridial "Anlagen" on segments two to eight. Those on seg- 

 ments five and eight persist and form the coxal gland and genital 

 system respectively, but the others degenerate and soon disappear. 

 He says nothing however, about a coalescence of the glands on the 

 fifth and sixth segments but remarks that the nephridium of the 

 sixth segment is the last of the transient ones to disappear. 



The source of the blood supply for the saccule is interesting; 

 somewhat difterent from that found in other arachnids, and so far 

 as I can gather, has not hitherto been described. Accompanying 

 the nerve from the brain mass to each of the appendages is an 

 artery; a well defined thick walled vessel. The artery which ac- 

 companies the nerve of the fifth appendage (NV), on reaching the 

 base of the appendage, sends off a branch {CA) at right angles to 

 its course direct to the saccule of the coxal gland (photo 4. The 

 course of the artery can also be traced intermittently in photos 1, 

 and 1 a). On reaching the coxal gland at the point where the sac- 

 cule comes nearly to the surface of the gland, the artery breaks 

 up, and the fluid, passing through a mass of cellular lymphoid tissue 

 which may be referred to as the glomus {GL photos 5, 5 a), forms 

 numerous capillaries, or rather lacunae, which hang into the lumen 

 of the saccule; forming glomeruli in the typical manner already 

 described in the introduction. 



So far the description of the coxal gland may be applied to 

 all scorpions but we now come to an accessory organ which is not 

 found in all of the families. 



KowALEvsKY first described this organ in ButJms occitanus from 

 the South of France, but remarks that he could not find it in 

 Androdonus, an allied Buthid from Russia. Androdonus is simply 

 a synonym for Buthus and his species was probably B. caucasicus. 

 He called it the lymphatic organ to distinguish it from the lymphoid 

 organ which lies above the nerve cord along its whole length in 

 the abdomen of all scorpions. According to Kowalevsky the lym- 



