200 PROCEEDINGS OF THE NATIONAL MUSEUM vol. lu 



The species Pseudozonitis marginata, which is presumably restricted 

 to the West Indies, has its nearest known relative in the Central Amer- 

 ican P. megalops (Champion). Inasmuch as P. marginata occurs as 

 far north as Andros Island in the Bahamas and as far south as Grenada, 

 its failure to colonize the mainland at either end of its range is likely 

 the result of an inability to compete with the mainland fauna rather 

 than of difficulty in crossing over to the mainland. P. obscuricornis 

 belongs to a species group that is otherwise recorded only from the 

 southwestern United States; however, the genus Pseudozonitis has 

 not been thorouglily studied in the Neotropics, and very likely other 

 related species will eventually be found in Mexico and Central 

 America, if not in South America. 



Finally, the relationships of the Cuban endemic Nemognatha oc- 

 cupata are so questionable that we prefer not to speculate on the 

 origin of this species. 



We conclude on the basis of the above analysis that the West Indian 

 meloid fauna derived from seven immigrant species, most or perhaps 

 all of which arrived on the islands from the neotropical part of the 

 mainland. Central America seems to have been the important source 

 region for West Indian Meloidae, although two of the species may have 

 reached the islands directly from South America. We find nothing 

 in the relationships and distribution of the Meloidae that is incom- 

 patible with the theory of origin of the West Indian fauna recently out- 

 lined by Darhngton (1957). 



Dispersal 



One important aspect of the meloid fauna of the West Indies not 

 mentioned in the preceding discussion concerns how Meloidae disperse 

 themselves. This aspect is also of more general significance because 

 it offers strong indirect support for the theory that the islands of the 

 West Indies are oceanic. 



As larvae Meloidae are parasitic either on grasshopper egg pods or 

 the contents of nesting cells of wild bees; as adults they are phyto- 

 phagous (except for a few species that do not feed). Various degrees 

 of host specificity are exhibited by different species both in the larval 

 and adult stages. Because of this general complexity of their ecology, 

 the Meloidae face special problems of dispersal, and it is therefore to 

 be expected that they would be poorly represented in any area having 

 a history of prolonged isolation. 



Significantly, 5 of the 9 New World genera of Meloidae whose first 

 instar larvae reach their feeding site by phoresy on adult bees are 

 represented in the West Indian fauna (Zonitis, Rhyphonemognatha, 

 Gnathium, Hornia, and Tricrania are absent) ; none of the nearly 20 

 New World genera of nonphoretic meloids (such as Lytta, Pyrota, and 

 the dominant genus Epicauta) occur there. Apparently, the West 



