NO. 8 HANNA AND HERTLEIN : MOLLUSCA 127 



This seems more plausible when it is noted that Pfeiffer had already- 

 described Helix pacifica from Cocos Island when he described cumin- 

 giana. O. /nariensi has nothing we can find to distinguish it from cumin- 

 giana, and pittieri is an exact sinistral counterpart. Apparently the last 

 is the dominant form and the identity has been recognized by von 

 Martens (1902, p. 60), Dall (letter May 24, 1902, quoted by Biolley), 

 and Biolley (1907, p. 15). 



Pilsbry segregated the Cocos Island species under a new section, 

 Ochrodermella. The type of Ochroderma is gigas, a very much larger 

 and heavier shell from the Caroline Islands. As genera are now consti- 

 tuted, it seems rather difficult to reconcile the union so we have given 

 the section generic standing. 



Ochrodermella biolleyi (von Martens) 

 Text figure 1 



Tornatellina biolleyi von Martens, Sitz. Ges. Naturf. Freunde zu Ber- 

 lin, Jahrg. 1902, no. 3, p. 60. "Cocos-Island." Biolley, 



Mollusques de L'lsla del Coco. Mus. Nac. de Costa Rica, 1907, 

 p. 16. Cocos Island. 



Tornatellina hopkinsi Sykes, Zool. Record, vol. 39, for 1902 [Issued 

 1903], Moll. p. 45. Costa Rica [No/nen nudum. See Biolley, 

 1907, p. 16, footnote 2.] 



Fig. 1. Ochrodermella biolleyi (von Martens). Length, 13 mm. 



