TABLE OF CONTENTS 



Introduction 531 



Table 1. Digenetic Trematodes Occurring in Both the Tropical 

 Pacific and Tropical Atlantic; Their Hosts and Dis- 

 tribution 533 



Table 2. Pairs of Geminate Species and Their Distribution 537 



Table 3. Pacific Species with Nearest Related Species in the 



Atlantic but with Ordinary Specific Differences . . 538 



Table 4. Pacific Species Occurring Elsewhere but Not in the 



Atlantic 539 



Species Collected from the Galapagos Islands and 



Their Relationships 540 



Table 5. Distribution of Nearest Relatives of Endemic Gala- 

 pagos Species ........ 540 



Distribution of Nonendemic Galapagos Species . 542 



Discussion • 543 



Summary 545 



Literature Cited 547 



