398 PROCEEDINGS OF THE ACADEMY OF ['"^ept., 



blood supply is similar therefore to that in European species of Haliotis, 

 as described by Perrier ('89), Wegmann '(84) and other workers. 

 Whatever function is served by the papillie, it is very evident, judging 

 from their appearance, that they are actively secretory by nature. 



The right kidney (fig. A, RK, RK') is the jDrincipal excretor}^ organ 

 in Haliotis. It is well developed and occupies, in the species under 

 discussion, a position very similar to that described for the European 

 species, H. tuherculata and H. glabra (Haller). From the small cham- 

 ber (IC) immediately behind the lobe (RU), serving as a mouth to 

 the ureter, tliere is a species of vestibule opening posteriorly into larger 

 cavities at the right (RK) and left {RK'). The junction of these is 

 under the forward inner corner of the pericardium (P), the vestibule 

 (/C) corresponding in position to the papillary sac. The last named 

 organ and the vestibule of the right kidney are separated by the rectimi, 

 which is supported between them by a thin dorsal and ventral partition, 

 shown to some extent in fig. 3. PI. XXX, although this section is too 

 far posterior to indicate clearly their true relations. 



Bouvier ('88) recorded an inter-renal communication in A7npuUaria, 

 but this is emphatically denied by Pelseneer ('96). Haller has reported 

 such a state of affairs in Haliotis '' glabra" and Trochus "gibberosus," 

 but very little acceptance has been accorded to the statement. Com- 

 munication may possibly exist in certain mollusca, but it is doubtful 

 if such a connection is present in the genus Haliotis. By referring to 

 figs. 1, 3,5 it will be seen that, in addition to the close contact of the 

 two nephridia as just explained, they are in close proximity at the 

 bottom of the chamber (IC). However, a careful examination of 

 several series of sections through these regions gives no hint of any 

 definite connection. 



From its junction with the vestibule the cavity of the posterior part 

 of the kidne}'' {RK') extends beneath the pericardium and around its 

 inner and posterior surface. The lumen of the anterior portion {RK) 

 is directed forward toward the columellar muscle. Xear the latter it 

 enlarges considerabl}' in a dorso-ventral direction, and becomes in shape 

 and size like an almond seed in specimens of a^'erage size. The outlines 

 of the walls of the kidney itself correspond closely with the cavities 

 just described, and accordingly are similar in all essential regards to 

 the species described b}^ Wegmann ('84), Totzaur ('02) and others. 



The tissue of the right kidney is nowhere verj'- thick; it is disposed 

 more as an intervisceral packing material. The division {RK') in 

 the region of the pericardial cavity is a "ciu'ved mass of spongy tissue, 

 lying under and about the inner side of the pericardium and ending 



