62 bartsch: subspecies of obba marginata 



The distribution of the groups outHned above is rather interesting. 

 The subspecies in which the dark coloration predominates are known 

 from Bohol, Camiguin, north of Mindanao and the islands of Olanivan, 

 Sarangani, and Balut off southeastern Mindanao. None of the dark 

 forms so far are known from the large island of Mindanao itself. The 

 broadly conic light-colored Obba marginata mearnsi and Obba marginata 

 ■palmasensis come from Sarangani and Palmas, respectively, both off 

 southeastern Mindanao. The light colored lenticular forms having 

 the basal peripheral color band well developed are so far known from 

 Samar, Leyte, Cebu, and northeastern Mindanao, and I strongly sus- 

 pect that the form recorded from Siquijor and that from Talisayan, 

 Mindanao, will prove to belong here. The light-colored lenticular 

 forms in which the basal peripheral band is obsolete are known from 

 western Mindanao and the island of Jolo. 



The following key may be of help in determining the known sub- 

 species^: 



Dark bands predominating over the hght zones. 

 Greater diameter more than 30 mm. 



Lines of growth strongly developed (Sarangani Island). 



saranganica Hidalgo. 

 Lines of growth not strongly developed (Balut Island). 



balutensis new. 

 Greater diameter less than 30 mm. 

 Basal bands very dark brown. 



Greater diameter more than 25 mm. (Camiguin Island). 



marginata Miiller. 



Greater diameter less than 22 mm. (Olanivan Island). 



* worcesteri Bartsch. 



Basal bands hght brown (Bohol Island) boholensis new. 



Dark bands not predominating over the light zones. 

 Light zones nmch greater than the dark. 

 Shell broadly conic. 



Peripheral basal color band moderately strong (Palmas 



Island) palmasensis new. 



Peripheral basal color band obsolete (Sarangani Island). 



mearnsi new. 

 Shell not broadly conic, lenticular. 



Peripheral basal brown band obsolete. 



Median band above and below reddish (Zamboanga, 

 Mindanao) zamboanga new. 



1 The types of the new subspecies are registered in the U. S. National Museum 

 under the following numbers: balutensis, no. 256548; boholensis, no. 116914; 

 palmasensis, no. 256420; mearnsi, no. 2,56423; lanaona, no. 2oM^b\' joloensis, no. 

 256549; samarensis, no. 256549. 



