no. 3636 MONOPHYLLUS — SCHWARTZ AND JONES 3 



Gary L. Ranck has supplied us with invaluable data on two of the 

 holotypes in the United States National Museum. 



All external measurements and weights, except for length of fore- 

 arm, are those recorded by the collectors on original labels. Skull 

 measurements and length of forearm were taken with vernier calipers; 

 all are standard and expressed in millimeters. Length of maxillary 

 toothrow is the alveolar length and greatest length of skull includes 

 upper incisors. All weights are given in grams. 



Systematic Treatment 



Six nominal forms of Monophyllus (excluding for the moment M. 

 frater and M. clinedaphus from consideration) vary in total length 

 from a low mean of 61 (Hispaniola) to a high mean of 78 (Dominica), 

 with the Jamaican population almost as large (mean 76) as the Domin- 

 ican specimens, and the Cuban and Puerto Rican material almost as 

 small (means 66 and 65) as the Hispaniolan bats. In general, other 

 external measurements follow this same trend; means for length of 

 forearm range from 36.9 on Puerto Rico to 42.1 on Dominica and St. 

 Lucia. Cranial measurements likewise show the same tendencies; 

 greatest length of skull varies from 19.0 (Puerto Rico) to 24.2 (Domi- 

 nica), with means from 19.9 (Puerto Rico) to 23.4 (Dominica). Length 

 of maxillary toothrow ranges from 6.8 (Puerto Rico) to 8.9 (Jamaica), 

 with means from 7.1 (Puerto Rico) to 8.5 (Jamaica). Cranial measure- 

 ments generally form a continuum (with Puerto Rican bats having the 

 smallest skulls and Lesser Antillean or Jamaican bats having the 

 largest) and are useful primarily at the subspecific level. Several cranial 

 features, however, suggest that we are dealing with two species rather 

 than one as would otherwise seem to be the case. 



One of the characters that was presumed to separate the Barbadian 

 M . plethodon from its relatives was the fact that the two upper pre- 

 molars (PM 2 and PM 3 in formal terminology) were so crowded 

 that the customary diastema between these two teeth was obliterated. 

 Comparison of a skull of M. plethodon with those of Monophyllus 

 from the Leeward and Windward Islands shows that this feature is 

 common to all Lesser Antillean specimens in that the space between 

 the upper premolars is narrow, much less than half the length of 

 the first tooth. On the other hand, this space in Greater Antillean 

 Monophyllus is long, being at least as long as half the length of the 

 first premolar, and often longer. We have been unable to determine 

 any other wholly consistent cranial or dental details and have placed 

 emphasis on this relatively trivial feature as a basis for distinguishing 

 two species (rather than six) among the living Monophyllus. We 

 are deterred from considering all Monophyllus as conspecific by the 



