Haddon — On Generative mid Urinary Ducts in Chitons. 233 



I have tlie verbal information of Dr. B. Hatschek that this is not 

 unique of its kind, since the ciliated funnel of Sipunculus exists at 

 first, and is degenerated in a later larval stage." 



Yan Bemmelen (12), in order to test the above results, studied 

 Ch.marmoreus (Fabr.), Ch. marginatus, and Chitonellusfasciatus, and 

 found, " with all desirable clearness, the opening of the kidney into 

 the pericardium, described by Mr. Sedgwick," and confirms the 

 latter's account of the general structure of the kidney, and neces- 

 sarily at the same time casts doubt upon Haller's interpretation. 

 He believes that Haller has confused the external duct with the 

 pericardial duct. The latter holds that the terminal portion of 

 the kidney duct, directly it turns at right angles to lead to the ex- 

 terior, is lined with flagellate cells, which very shortly pass into the 

 ciliated cubical cells which line the remainder of the efferent duct. 

 Van Bemmelen suggests that the flagellate portion arising from the 

 kidney-duct opens into the pericardium; and that the ciliated duct, 

 which certainly opens to the exterior, arises from the kidney-body 

 and not from the kidney-duct, as Sedgwick had previously stated. 

 Van Bemmelen concludes by saying : — " Although Dr. Haller and 

 I have not examined the same species as Mr. Sedgwick, yet I am 

 disposed to believe that the differences between his description and 

 that of Mr. Sedgwick's and my own are not referable to variations 

 of the species." 



In reply to this criticism, Haller (13) states that he does not 

 deny that the pericardial orifice may occur in some Chitons, and 

 might naturally be expected to occur in Chitonellus, and in those 

 Chitons which have a short row of gills, but that it does not occur 

 in his species, though it may do so in Sedgwick's and Van Bemme- 

 len's. He maintains the correctness of his former interpretation, 

 and recalls the small blind diverticulum from the terminal kidney 

 duct (Nierenendgang), and says : " I now believe that in this di- 

 verticulum is to be seen the rudiment of a former ancient opening 

 (ciliated funnel, ' Wimpertrichter ') into the pericardium in Ch. 

 sicuhis and Ch. fascicular is, which opening, according to the state- 

 ments of A. Sedgwick and Dr. Van Bemmelen, is said to be found in 

 other forms " (I may add, though he does not refer to the fact, that 

 in Haller's figure 36 (11) this diverticulum (;() is ciliated). Haller 

 clearly suggests that a pericardial duct, where it exists, opens into 

 the terminal portion of the kidney duct immediately before the 



