On Certain Points in the Anatomy of Chiton. By 

 Adam Sedgwick, M.A., Fellow of Trinity College, 

 Cambridge. 



An account of the structure of the kidney of Chiton has 

 long been a want in morphology. Middendorff,^ in 1848, 

 described a branched gland lying ventrally on each side of the 

 body cavity which he identified as kidney j but he records 

 no observation on the structure of the gland, and expressly 

 states that he was not able to make out its opening or 

 relation to other organs. SchiflF,^ ten years later, was unable 

 to find this gland in Chiton piceus, and throws doubt on 

 MiddendorS^'s interpretation of its function. 



Von Jhering^ has comparatively recently recorded some 

 observations on the kidney of Chiton, and starts from the 

 position that no kidney is known in Chiton, Middendorfi''s 

 view as to the nature of the branched gland having been 

 sufiQciently refuted by Schiflfs later observations. Von 

 Jhering states that in the species of Chiton observed by 

 him the kidney consists of a branched gland lying ventral to 

 the rectum in the hinder part of the body cavity, and that 

 it opens by a single median pore ventral to the anus. He 

 further figures this opening. 



While staying at Herm this summer I found a fair 

 number of a good-sized species of Chiton — Chiton discrepans ; 

 and the results which I have obtained from the study of the 

 anatomy of this form, especially those which concern the 

 kidney, seem to me sufficiently important for immediate 

 publication. In the first place, I may mention that I have 

 seen nothing in any of my dissections or sections which in 

 the least supports von Jhering's statements as to the exist- 

 ence of a median renal duct and opening; and that my 

 observations are entirely opposed to the conclusion arrived 

 at by this investigator as to the unpaired nature of the 

 kidney of Chiton. On the contrary, Middendorff's observa- 



' ' Memoires de I'Acad. de St. Petersbourg/ 6th ser., vol. vi. 



2 Schiff, ' Zeit. f. Wiss. Zool.,' Bd. ix. 



3 ' Morpliol. Jahrbuch,' Bd. iv. 



