396 Bulletin American Museum of Natural History. [Vol. XX, 



coloration, and cranial details. A skull, without skin, from 

 near San Jose, Costa Rica, is also indistinguishable from the 

 adult Boqueron skulls. Apparently T. /. chiriquerisis will 

 be found to range from Costa Rica to the Cauca region of 

 western Colombia. A young specimen, from Boquete (alt. 

 5500 feet), Chiriqui, has the light area clear white, but in 

 cranial characters agrees with the Boqueron specimens. 



The relation of Cope's Myrmecophaga sellata, already re- 

 ferred to, to T. t. chiriquensis and T. t. tenuirostris can only 

 be determined by an examination of a series of specimens 

 from the type locality. 



The four subspecies of Tamandua tetradactyla above de- 

 scribed fall into two groups characterized by the character of 

 the rostral portion of the skull, as follows: 



A. Rostral portion of the skull short and broad, with the ratio of 



nasals to occipito-nasal length as 35 to 100, and the ratio of the 

 greatest breadth of the skull at the anterior edge of orbits to 

 the occipito-nasal length as 28.5 to 100; length of nasals about 

 equal to width of braincase. 



a. Size small (occipito-nasal length, 118) instabilis. 



b. Size medium (occipito-nasal length, 124.5) chapadensis 



B. Rostral portion of the skull long, with the ratio of nasals to occipito- 



nasal length as 39 to 100 ; nasals much longer than the width of 

 the braincase. 



a. Rostral portion of the skull narrow; ratio of greatest breadth of 



skull at anterior edge of orbits to occipito-nasal length as 24.4 

 to 100 tenuirostris. 



b. Rostral portion of skull broad; ratio of greatest breadth of skull 



at anterior edge of orbits to occipito-nasal length as 27.5 

 to 100 chiriquensis. 



EXTERNAL MEASUREMENTS OF 19 SPECIMENS OF Tamandua tetra- 

 dactyla instabilis. 



[The determination of the sex of the Santa Marta series has been 

 made from an examination of the skins, adults being readily dis- 

 tinguishable by the presence of a pectoral pair of well-developed 

 nipples in the females. The absence of nipples has been taken to 

 indicate males. Where no sex is indicated the specimen is a skull 

 or skeleton, and hence the sex indeterminable. The external measure- 

 ments, "total length" and "tail," are from the collector's labels. 

 All the specimens are from Bonda, near Santa Marta, Colombia.] 



