79^ General Notes. [July, 



scribes the coxal glands of Scorpio, and also finds that the coxal 

 glands of My gale are elongated and lobed as in Limulus. He 

 remarks : " Possibly such coxal glands are in all cases the modi- 

 fied and isolated representatives of the complete series of tubular 

 glands (Nephrida) found at the base of each leg in the archaic 

 Arthropod Peripatus." As will be seen in the foregoing note on 

 Peripatus, that animal is provided with a series of paired organs 

 which Moseley and Balfour, with Sedgwick, regarded as Nephrid- 

 ia, homologous with those of Chaetopod worms. 



It now appears that homologous organs exist in a third type of 

 Arachnida, for not only do the spiders and Pedipalpi possess 

 coxal glands, but also the mites. In his excellent " Observations 

 on the Anatomy of the Oribatidse," in the February number of 

 the Journal of the Royal Microscopical Society, Mr. A. D. 

 Michael describes a sac which he believes to be glandular, and 

 which he calls the " super-coxal gland." The organ was first 

 recognized in the mites of this family by Nicholet, who supposed 

 it to be connected with what he and others imagined to be the 

 stigma. 



When the upper part of the cephalothorax, and the adipose tissue 

 which underlies it, has been removed, " what appears to be the 

 enlarged, blind end of a fine colorless sac, may be seen on each 

 side of the body, the seemingly blind end being nearest to the 

 eye ; the sac descending obliquely downward and slightly forward, 

 and being attached close to the acetabulum of the coxa of the 

 second leg; a closer examination shows that this is not the only 

 attachment, but that the lower end is apparently bifurcated, and 

 that the second branch is attached much nearer to the center of 

 the body, and higher in level than the coxal branch. On dissect- 

 ing out this sac, and carefully extending it, a matter by no means 

 easy, it will be found that what seemed to be the blind end was 

 not the end at all, but that the whole organ is an elongated sau- 

 sage-shaped sac, bent upon itself in the middle and taking a sin- 

 gle turn, so that the two halves cross, but for some distance the 

 two limbs of the horseshoe (if 1 may call them so) lie over each 

 other, or are so closely pressed against one another as to appear 

 one ; it is only toward the end, that they stand free from each 

 other when in situT 



Mr. Michael suggests that these glands are analogous to the 

 nephridia (segmental organs) of Vermes, and the green gland of 

 Astacus and other Crustacea, and the coxal glands in scorpions 

 and Limulus. The resemblance to the segmental organs of worms, 

 especially the leech, is very considerable as regards the general 

 form of the organ, and to a lesser extent in the minuter struc- 

 ture, and if the double lines described in Michael's account be 

 tubules, " they would be analogous to those in the nephridia. 

 The sac (super-coxal gland) would correspond with the gland in 

 the nephridium, and the globular body with the vesicle." 



