020 



REPORT OF NATIONAL MUSEUM, 1902. 



forms. The plates are definitely separated in the specimens from St. 

 Thomas, Porto Rico, and Mona. 



Neither can I discover an}" difl'erence in the situation of the nostril 

 with reference to the two nasal plates between which it is located. 



The difference in the number of femoral pores is a real one, altliouo^h 

 it is only shown in the average and the figures intergrade considerably; 

 in fact the range of individual variation in A. exul covers the extremes 

 of A. alhoguUata. Thus in sixty-seven specimens of A. exul from 

 Porto Rico and St. Thomas the number of femoral pores varies between 

 12 and 18. Of these sixty-seven specimens, 61 per cent have 15 and 

 16 pores, while 12 per cent have 11 and other 12 per cent have 17 

 pores. In sixteen specimens of A. alhoguttata the number of pores 

 varies ])etween 12 and 15. Of these sixteen specimens, more than 81 

 per cent, have 12 and 11 pores. The exact averages are, for A. 

 exul 15.1, and for A. alhogiMata 13.3. Curiously enough there seems 

 to be an aversion for the numl^er 13, as only one specimen in sixty- 

 seven of the former and one in sixteen of the latter have 13 pores. 

 Although the series of A. cdhoguttata is comparatively insignificant, it 

 seems safe to conclude that the great majority of this form have 12 

 to 14 femoral pores, while most A. exul have 15 to 16. 



From the tables published hj Mr. Meerwarth,® one might be led to 

 suppose that there is a fairly constant difference between the two 

 forms, consisting in the greater number of labials in A. exxil., as the 

 average number of supralabials is ^.'o and of infralabials 6.1 in the lat- 

 ter against supralabials 6.0 and infralabials 5.1 in A. alhoguttata. This 

 result, which is entirely at variance with what I have obtained, is 

 probably due to his scantier material. At first I suspected that the 

 discrepancy might l)e due to a real difference between the St. Thomas 

 specimens and those from Mona, and that the Porto Rican specimens, 

 of which he had none, might be intermediate. I consequently arranged 

 my series from the three islands separately, with the following result: 



Locality. 



St. Thomas, 10 specimens 

 Porto Rico, 48 specimens . 

 Mona, 7 specimens 



Supra- Infra- 

 labials. labials. 



6.1 

 6.1 

 6.05 



5.2 

 5.1 

 5.1 



It will be seen (1) that my Mona specimens agree with Meerwarth's 

 from the same island; (2) that my St. Thomas and Porto Rican speci- 

 mens average nearly the same, and (3) that they also average the same 

 as the Mona Island specimens. It seems therefore pretty safe to con- 

 clude that there is no difference in this respect between the two forms. 



«Mitth. Naturh. Mus. Hamburg, XVIII, 1901, pp. 30-33. 



