230 NILS HJ. ODHNER 
Amphidoxa helicophantoides Pfeiffer. — Masatierra (Aug. 1917): the 
Yunque quebrada, | sp., d. 3,5. — Rabanal, in the bottom, about 100 m above 
sea, 2 small sps., and about 300 m, 2 small sps. — Pangal, on ferns, under 
leaves, I sp., d. 3,5. — Beneath Damajuana, thick forest, about 300 m, I sp., 
d. 4. — Puerto Frances, about 400 m, numerous sps., d. 4.44 mm. — Puerto 
Ingles, about 400 m, thick forest, I small sp. — Centinela Ridge, about 350 m, 
thick forest, 2 shs., max. d. 2,5 mm. 
Remarks on the Genus Amphidoxa. 
The typical forms of this genus are the two species mentioned above, 
which are indigenous in Juan Fernandez and found there only. Their anatomy 

Fig. 8. Teeth from the radula of Amphidoxa helicophantoides Pfeiffer.  X 750. 
Fig. 9. Teeth from the radula of Amphidoxa marmorella Pfeiffer. The lower row somewhat 
aberrant. XX 750. 
Fig. 10. Jaw of Amphidoxa marmorella. X75. 
has been unknown, but judging from the shell characters, PILSBRY (1894) has 
included the genus in the fam. Lxdodontidae. 
Since all the material collected by the Swedish expedition was dry, except 
one small specimen in alcohol, I could not make the organization of the animal 
subject to a thorough examination. The radula and the jaw, however, were 
studied, and found to be typically endodontoid, the jaw (fig. 10) being composed 
of band-like plates (in A. marmorella about 20—22 in all, in A. helzophantoides 
about 30), the teeth having squarish basal plates, and the lateral ones bearing 
3—5 denticles. In both species the median tooth has an unusually small apex 
(quite as in Exdodonta involuta from Juan Fernandez described above), but this 
is subject to some variation, like the number of teeth and their shape, too. 
In a specimen of A. helicophantoides the radula (fig. 8) measured 0,9 mm in length 
