no. 3635 MONOPHYLLUS — SCHWARTZ AND JONES 17 



worthy of recognition as an entity distinct from M. p. luciae. We 

 are deterred from so considering M. p. j rater by the fact that all skulls 

 are incomplete, usually grossly so, and by the lack of specimens 

 on which pelage characters and external measurements can be ascer- 

 tained. We therefore retain M. p. jrater with full knowledge that 

 it may prove later to be synonymous with M. p. luciae. Retention 

 of the name at this time permits its convenient use in dealing with 

 the larger of the two species of Monophyllus from Puerto Rico. 



Specimens examined. — Puerto Rico: Cueva Catedral, Morovis, 

 Arecibo, 3 (AMNH 40942-44). 



Discussion 



The genus Monophyllus is composed of two species, each with 

 three subspecies, which, except for the sympatric occurrence of 

 representatives of each species on Puerto Rico, are allopatric. One 

 species (M. redmani) is Greater Antillean in distribution and the 

 other (M. plethodon) is Lesser Antillean, except for the occurrence 

 (only in the past?) of a population on the island of Puerto Rico. 

 Such a picture suggests that there have been two independent centers 

 of differentiation of Monophyllus in the West Indies with the re- 

 sultant evolution of two practically allopatric species. The Lesser 

 Antillean M. plethodon, however, succeeded in crossing the Anegada 

 Passage and reached Puerto Rico at a time when that island was 

 occupied also by M. redmani. Clear evidence of immigration from 

 the Lesser Antilles to the Greater Antilles (in contrast to the reverse 

 situation) is quite rare in the terrestrial vertebrate biota of the 

 Antillean islands, and M. plethodon stands out as an invader of the 

 Greater Antilles from the south. 



The degree of differentiation of the subspecies of M. redmani 

 (in contrast to those of M. plethodon) is striking. The races of M. 

 redmani (M. r. redmani, M. r. clinedaphus, M. r. portoricensis) all are 

 distinctly different, the primary difference being in overall size and 

 concomitantly in size of skull. Although perhaps interpretable as 

 grossly clinal, with the largest subspecies in the west (M. r. redmani) 

 and the smallest in the east (M. r. portoricensis) , the size difference 

 is not quite so diagrammatically demonstrated as one might assume 

 from first glance. The subspecies M. r. redmani and M. r. clinedaphus, 

 for instance, have comparably long forearms despite a distinct di- 

 chotomy in overall size; secondly, the occurrence of M. r. clinedaphus 

 on two islands (Cuba and Hispaniola) , rather than each island having 

 its own subspecies, suggests also that we are not dealing with variation 

 of a typically clinal nature. 



In contrast to the subspecific differentiation in M. redmani, the 

 races of M. plethodon are much less distinctly defined. In fact, were 



