1892.J THE LAND-MOLLUSCA OF THE PHILIPPINES. 465 



Balabac. The mistake about " Palawan passage," alluded to above, 

 has perhaps induced collectors to assign to both sides of the supposed 

 " passage " species that really came from one side only. The only 

 form that appears to have any real authority as coming from Borneo 

 is H. dorice, Dohrn, and I do not feel absolutely certain even about it, 

 while Dohrn himself is very doubtful. But, whether the group be 

 represented in Borneo or not, it is interesting to consider the relation- 

 ship of these two very isolated groups of Helices, which, it may be 

 remarked, afford very strong evidence for a land connection at 

 some point between Mindoro and the Calamianes. It appears to 

 me that both of these groups find their nearest relations in an 

 easterly and not in a westerly direction — the Phoenicobius group 

 being nearly akin to the well-known forms mamilla and papilla, from 

 N. Celebes, and these to concisa, F^r., from Waigiou, and quoyi, 

 Desh., from Celebes ; the polychroa group to shells of the type of 

 rehsei, Mart., from N. Guinea, and dupuyana, Cpr., from N.E. Aus- 

 tralia. It is certain that, as far as these regions are concerned, it is 

 only in N. Guinea and N. Australia that Helices are found of the 

 size and general texture of those under consideration. And it is 

 perhaps worth while pointing out other affinities of the same kind. 

 The remarkable H. antiqua. Ad. & Rve., from N. Borneo, appears 

 closely allied to no other shell but leonardi, Tapp.-Can., from 

 N. Guinea. The unique H. plurizonata. Ad. & Rve., found during 

 the ' Samarang ' voyage in Mindanao, is very nearly related to 

 lacteolota, Sm., and agnocheilus, Sm., both from N. Guinea \ The 

 CorasicB of the Philippines are closely related to a group of shells 

 which attain their maximum development in the Solomon Islands. 

 The section of Chloritis which includes such Helices as quieta, Rve., 

 brevidens. Shy., spinosissima, Semp., saulics, Pfr., sanziana, H. & J., 

 caliginosa, Ad. & Rve., and philippinensis, Semp., has its nearest 

 relations in N. Guinea, Torres Str., and N. Austraha. And it is 

 perhaps worth noticing that the Philippine Chlorites just mentioned 

 appear to be restricted to the two islands of Mindanao and 

 Mindoro, i. e. just where the two ridges of connection impinge upon 

 the Philippine group. 



These facts seem to point to a land connection, no doubt of 

 extreme antiquity, which admitted of Land-Shells of a Papuan and 

 N. Australian type finding their way in a westerly direction. I am 

 therefore inclined to regard Phoenicobius and the polychroa group, 

 as now occurring in Palawan, Mindoro, and the adjacent islands, 

 as a sort of survival of a fauna which perhaps had once a much more 

 extended range. It is a significant fact that almost the only other 

 Helix from the E. Indies generally which in shape at all approaches 

 the smaller forms of the Phoenicobius group is M. codonodes, Pfr., 

 from the Nicobars. It is possible that eventually fossil or subfossil 

 forms may be discovered in Sumatra and Java which will place 

 this at present isolated form in continuous geographical connection 

 with the apparently related fauna of Busuanga and Mindoro. 



^ Had the ' Samarang ' been anywhere near N. Guinea, one might have 

 been disposed to beheve that the locality for phirisonata was erroneous ; its 

 facies is so strongly Papuan. 



