MOLLUSCA FROM JUAN FERNANDEZ AND EASTER ISLAND 



253 



Though the external appearance of this species — shape, colour, and 

 sculpture — are extremely like those of Stephanoda tessellata (only relative 

 dimensions of whorls and umbihcus are different), its apertural equipment (which 

 is rather difficult to discern except in strong penetrating light) proves it to be 

 a member of the Thamnatodon- group of Endodonta ; the most akin species 

 may perhaps be E. occulta from Masatierra described above. 



Only one specimen of this species was collected. 



Siiccinea masafuerae n. sp. Fig. 24. — Shell extremely thin and fra- 

 gile, ovate, with a minute papiliiform spire only a sixth of the shell height, 

 well-rounded whorls, and a large, ovate aperture occupying % of the shell 

 height. Colour yellowish horn-green. Sculpture: dense and rather marked lines 

 of grouth together with a fine crossing striation very similar to that o^ S. texta 

 (see above). Dimensions: height 6,5, breadth 4 mm; whorls 2^/3. 



24 



Fig. 23. Endodonta skottsbergi n. sp. X M- 

 Fig. 24. Succinea masafue?-ae n. sp. X 4. 



The crossed striation is a character which this species shares with S. 

 texta from Masatierra, which thus may be considered as its nearest ally. The 

 present form is however thinner and lighter in colour; further its shape is 

 different, inasmuch as the spire is much shorter and not produced like that 

 of vS. texta. These characters clearly show the specific distinctness of the pre- 

 sent form, of which unfortunately only four much defective specimens were 

 found. 



