678 REPORT OF NATIONAL MUSEUM, 1902. 



referred to ^4. cseca by Strauch and mentioned above. In addition I 

 have before me a .specimen (U.S.N.M. No. 11715) from St. John, 

 probably one of the types of A. fenestrata. In all these 11 specimens 

 the body rings vary only between 242 and 250 and the caudal rings 

 between 13 and 16. I may further add that our specimen agrees 

 exactly with the other details recorded by Boulenger in his description 

 of the 3 specimens in the British Museum, namely, 2 temporals, 4 to 

 6 preanals, 12 to 14 segments above the lateral line and 14 below in a 

 ring around the middle of the body. Finally, Reinhardt and Luetken 

 mention one temporal (or postocular) as an exception. Even if we 

 include the so-called A. caeca from St. Thomas as an abnormal speci- 

 men, having the nasals contiguous behind the rostral, it will be seen 

 that in this series of 11 specimens the individual variation is but very 

 slight. This result tallies exactly with that obtained from an examina- 

 tion of 19 Porto Rican specimens of one species, the largest series yet 

 compared anywhere, showing that these animals exhibit a most unex- 

 pected small variability in certain characters contrary to what was 

 formerly believed to be the case. 



An examination of the five specimens of Amphisbaena collected at 

 Lares by Mr. Baker shows that they fall into two groups. The first, 

 consisting of three specimens, has 221 to 230 body rings and 17 to 19 

 rings on the tail; 1 postocular +1 temporal; nasal suture short, not 

 longer than portion of rostral visible from above, or entirely lacking, 

 the rostral in one specimen being barely in contact with one of the 

 prefrontals; color, darker. In the other group of two specimens the 

 rings on the body are 249 and 251 and on the tail 16; a single post- 

 ocular and no temporal; long nasal suture, it being about three times 

 longer than the portion of the rostral visible from above; color, paler. 

 Preanals, number of segments around the body, and postmental scutes 

 nearly alike in both groups. 



The fact that these specimens were collected in the same locality, 

 and the evident close relationship of the two groups, at first suggested 

 that we had to deal with a rather extreme case of individual variation. 

 On the other hand, the correlation of such a great number of charac- 

 ters with no indication of intergradation, viewed in the light of the 

 conclusions arrived at from a study of the forms collected in the other 

 islands, convinced me of the specific distinctness of the two groups of 

 specimens. 



This conclusion, which I had arrived at before my visit to Porto Rico, 

 was amply sustained by the material brought home by me or received 

 since my return. This material consists of 17 additional specimens, 16 

 of which belong to the group having a short nasal suture, 1 temporal, 

 and 220 to 230 body rings, while the seventeenth specimen is as typical 

 of the other group, having a long nasal suture, no temporal, and 250 

 body rings. 



