250 PEOFESSOR F. M. BALFOUR. 



The vesicular portion is lined by columnar cells, with very 

 large oval nuclei, -svliile the duct is lined by cells similar to 

 the epidermic cells, with which they are continuous at the 

 opening. 



In the last (17th leg) of the males of this species, this gland 

 (vide above, note 4) possesses a slit-like opening placed at 

 the apex of well-developed white papilla (PL XIV, fig. 4). 

 It is enormously enlarged, and is prolonged forward as a long 

 tubular gland, the structure of which resembles that of the 

 vesicles of the crural glands in the other legs. This gland lies 

 in the lateral compartment of the body cavity, and extends 

 forward to the level of the .9th leg (PI. XV, fig. 8, and 

 PI. XX, fig. 43). It is described by Professor Balfour as the 

 accessory gland of the male, and is seen in section lying 

 immediately dorsal to the nerve-cord in fig. 20, a g^ 



PART III. 



The Development or Peripatus capensis. 



[The remarkable discoveries about the early development of 

 Peripatus, which Balfour made in June last, shortly before 

 starting for Switzerland, have already been the subject of a 

 short communication to the Royal Society (' Proc. Roy. Soc' 

 No. 222, 1882.) They relate (I) to the blastopore, (2) to the 

 origin of the mesoblast. 



Balfour left no manuscript account or notes of his discovery 

 in connection with the drawings which he prepared in order 

 to illustrate it, but he spoke about it to Professor Ray Lan- 

 kester and also to us, and he further gave a short account of 

 the matter in a private letter to Professor Kleinenberg. 



In this letter, which by the courtesy of Professor Kleinenberg 

 we have been permitted to see, he describes the blastopore as an 

 elongated slit-like structure extending along nearly the whole 

 ventral surface ; and further stales, as the result of his exami- 

 nation of the few and ill-preserved embryos in his possession. 



