232 



NILS HJ. ODHNER 



described for ^. hookeri. The same undivided appearance is met with in other 

 forms of Stephanoda, e. g. S. lirata Couthouy. There are no appendages of 

 the mantle margin. 



More important differences are exhibited by the genital organs (fig. ii). 

 These are in S. quadrata arranged and constructed thus: In the beginning of 

 the third whorl the hermaphrodite gland is situated embedded in the superior 

 lobe of the liver. It consists of two separate clusters each containing 5 (the 

 upper) or 6 (the lower one) finger-like lobes. The thin hermaphrodite duct soon 

 immediately widens to a long ampulla, with broad and irregular dilatations on 



its outer wall, then it narrows again, 

 and runs towards the inside of the 

 albuminiparoiis gland. Here a lengthened 

 vesicula seminalis is attached which is 

 embedded in the albuminiparous gland 

 and only projects with its upper flexed 

 end. The next portion of the herma- 

 phrodite canal is rather wide, and intim- 

 ately connected with the oviduct into 

 which it soon debouches; no special 

 prostata gland is developed. The oviduct 

 is produced upward and downward ; from 

 its median portion the muscular vagina 

 sets out and from its lower end the vas 

 deferens takes its origin. At the point 

 where the vagina begins a long-stalked 

 spermatheca is attached; it extends 

 along the oviduct upwards and is covered 

 by this, only the apical end of the sperma- 

 theca projecting beyond the oviduct. 

 Whereas the vagina is a simple 

 tube without any accessory equipment, 

 the male organ is somewhat unusually 

 appointed. The vas deferens has the 

 usual course beneath the retractor of the ommatophore, and then, after some 

 coils, debouches into the apex of the greatly widened penis, near the insertion 

 of its retractor muscle. Somewhat distally of this point, the penis is furnished 

 with a thread-like winding appendix or flagellum, and a similar organ is attached 

 far more distally, about halfway its length. 



Thus the genital organs are relatively simple, approaching the type of 

 Pyramidula with respect to the long-stalked spermatheca, but there is a 

 singular differentiation in the two appendices of the penis, features which have 

 their nearest analogon in the genus Sagda from the Greater Antilles. I have 

 found the same structure of the penis in another specimen of the genus, S. lirata 

 Couth., from Lagotowia, Tierra del Fuego. 



The radula of the two Juan Fernandez Stephanoda species is helicoid, 

 inasmuch as the teeth have squarish basal plates, and the marginals have three 

 or more subequal cusps. As a common feature may be mentioned the smalJness 



Fig. 1 1 . Genital organs of Stephanoda quadrata 

 F^russac. a albuminiparous gland jy? flagellum; 

 h hermaphrodite gland; o oviduct; p penis; 

 r. p. retractor penis; r. t. tentacular retractor; 

 sp spermatheca; v. d. vas deferens; v.s. vesi- 

 cula seminalis. 



