380 DR. p. L. SCLATER ON NEW AMERICAN BIRDS. [NoV. 26, 



conical bill, in which it differs from all the allied species that I am 

 acquainted with. The first, second, and third primaries increase 

 gradually in length, the fourth and fifth being equal and longest. 

 The tail is imperfect, but the lateral rectrices appear to have been 

 shorter and graduated as in other allied forms. 



Fam. FoRMiCARiiD^. 



5. Thamnistes ^quatorialis. 



Similis Th. anabatino, seel supra oUvaceus obscurior, et pileo ru- 

 fescentiore, ferrugineo tincto, rostroque magis compresso di- 

 ver sus. 



Long, tota 5"5, alse 2'9, caudae 2*2. 



Hab. In rep. ^Equatoriana. 



The genus Thamnistes appears to belong to the neighbourhood of 

 Thamnophilus proper, with which it agrees in its thick, strong, com- 

 pressed bill and general characters. I am also inclined to believe 

 that the curious BraziHan form, Biatas nigropectus (Lafr.), agreeing 

 as it does in general characters of structure and plumage, must be 

 placed near it. Mr. Salvin received many examples of Thamnistes 

 anabatinus in the collection made at Choctum in Guatemala in 

 1859-60, and beheves that the birds with the large concealed sub- 

 interscapular spot are the males, and those without it the females of 

 this singular form. If that is the case, which I think probable, my 

 specimens of Thamnistes cequatorialis are both males, each of them 

 possessing the interscapular spot. But neither of them are very 

 perfect specimens, — one, obtained through M. Verreaux, and stated 

 to be from the Rio Napo, being in moult, and the other, collected 

 by Mr. Eraser at Nanegal, having been badly shot. I have, how- 

 ever, no doubt of their belonging to a second species of this curious 

 form of Thamnophilinee. 



6. Ramphoc^nus sanct^ marth^. 



Similis R. rufiventri ex Guatemala, sed major, colore capitis 

 tnulto minus rufescente, et ventre toto pallide fulvo, minus ru- 

 fescente, dorso dilutius cinereo diversus. 



Long, tota 5"4, alae 2"2, caudse 2'0, rostri a rictu 11. 



Hab. In rep. Nova Granada, regione boreali littorali. 



The comparison of a specimen of the true Guatemalan Rampho- 

 ccsnus rufiventris, kindly presented to me by Mr. O. Salvin, with 

 the present bird from Sta. Martha, has forced me to recognize them 

 as different species, contrary to what I supposed when I wrote my 

 "Synopsis of the American Ant-birds" in these 'Proceedings*,' 

 where the Santa-Martha bird is described under the name R. rufi- 

 ventris. Though nearly allied, however, it is a larger and less de- 

 cidedly coloured species, easily recognizable on comparison, and 

 makes the fourth of the group. 



* See P. Z. S. 1858, p. 244. 



