2o6 KINGSLE V. [Vol. \- 1 1 1 . 



Comparisons. — The foregoing account differs in some points 

 from that which I gave in 1885. I then failed to recognize the 

 genetic connection between the nephridium and the coelom and 

 also failed to recognize the closed condition of these organs. 

 The history of our knowledge of the nephridia in Limulus can 

 be briefly summarized. 



These organs were first noticed by Packard ('75^) who from 

 their histology and by exclusion, concluded that they were 

 renal in function and homologous with the green gland of 

 Crustacea. Five years later ('80) he redescribed and figured 

 their adult structure and suggested a comparison in their 

 position with the shell gland of the Entomostraca. Lankester 

 in 1882 described these organs and compared them with the 

 coxal glands of the scorpion and later ('84) gave the histology 

 with some detail. In both papers he was inclined to compare 

 them with the green gland of the Crustacea but still admitted 

 the possibility or even probability of their being ectodermal 

 or entodermal with a frame work of " skeletotrophic tissue." 

 In the next year Gulland ('85) described the organ in young 

 specimens while Kingsley at the same time gave an account of 

 the early history of the organ, comparing it exactly with the 

 shell dand of the Entomostraca and claimed that it and the 

 o-enital ducts of both Crustacea and Arachnida should be 

 regarded as Nephridia. In 1890 Kingsley stated that the 

 coxal gland of Limulus was derived from the coelom of somite 

 V, that it terminated caecally and gave in outline the above 

 account of the origin of the segmentally arranged lobes. Kish- 

 inouye ('91^) stated that in Linndus longispmus the coxal gland 

 is formed from the ventral part of the coelom of somite V 

 and later ('91^) describes the method more at length. His 

 account agrees well with the foregoing excepting that the out- 

 growths of the metameric lobes occur at an earlier stage and 

 the end sac (his "funnel") is in the mesoblastic dissepiment 

 between the fifth and sixth appendage bearing segments. 



All others who have had occasion to refer to the nephridia 

 of Limulus have used the material included in the papers 

 enumerated above. This is true of Eisig ('88) Loman ('88) and 

 Sturanay ('9i). 



