Anatinc Cicnus Ni/nxd (hid lis Xcanst Mlics. 1(»'.) 



Ilyonetta HEINE. Nomciicl. Mns, II. •in. oniiili.. is'jo. p. ;;17 (iiom. eineud. 

 |.i(. Xi/roca Fleming, iM'ii ; lyiu-. i licivlmv. \ii'i^ in/nx-u fiiildcustiidt). 



Diagnosis.— Shmhw \» I'liliiinhi. ImH Iciiulli of win- less than r, limes 

 (iio length of expubrd ciiiiiKMi : iicnd \\illi<Hil .-i Lmg occipital crest. 



Description.— WhvA 4LV.V4 4/.". times tlic Iciijitii ol" exposed culmeii ; l)ill 

 relatively somewhat flattened terminally, its width near end 1-12/10 times 

 its width at hase, its tip rcunded. its width at itosterior end of nail 1 !>/10- 

 •_':;/10 times the length of iinil: lip nt m.-ixiiin much hooked; nail of Idll 

 broad and triangular: heii,'hl ef In!! m eMreme hase 0/10-12/10 times its 

 ,-r(>atest \Yidth ; base of cidmeii imi deeply ceiicave: exposed culmen 14/5- 

 I'l/.") times the height of hill at I'xlreme base, and 10/10-2 1/3 times the 

 greatest width of hill: exposed ciiliueii de.-idedly less than the lengtli of 

 inner toe with claw: anterior outline of featliering at the hase of culmen 

 triangular and acutely pointed : Ceallierinir on sides of maxilla not n^aching 

 forward as far as that at the lia>e of culmen : a short occipital crest or none. 

 Tiii)C. Anas nyroca GiilihMisriidl. 



Remarks. — The species included undei- this heading seem at first sight to 

 he a heterogeneous assend)lage. hut. as in the case of Fiili.r. the examination 

 and comparison of all the specie; iinnlved nnd the proper consideration of 

 individual variation show that no further generic division is possible with- 

 out virtually making a genus of encli species on characters either trivial 

 tn- not wholly constant. It is (piite true that Xi/roca americana differs in 

 structure considerably fnun Xi/rocfi in/r:i('i. the length of the wing in the 

 f(U'mer being more than 4 1/2 times the exposed culmen; the bill less wid- 

 ened at tip. its width at posterior end of nail le-:s in proportion to the length 

 of the nail, its height at extreme base decidedly more than its greatest 

 width; and the length of the exposed culmen decidedly more than 2 times 

 the greatest width of bill : but all these ditTerences are more or less unsat- 

 isfactory, as they either by individual variation or through the characters 

 of other species here referred to Xi/i-nca gi-ade insensibly into each other. 

 The same situation exists in the other species. Two forms. Xyroea natioui 

 and Xyroea innotata. have not been examined in the present connection, but 

 the relationship, of at least the lattei-. in s<i far as detevminable, seems to 

 be doubtless with the i)resent group. 



\o c(unp]ication exists in the generic synonymy of this group, for the 

 name Xyroea Fleming' has for its tyiie by tautonyiuy Anas nyroca Giilden- 

 sliidt. The Ilyo/ietta of Heine- is. of coui-se, merely a substitute name for 

 Xyroea Fleming, for rea.sons of lauism. 



The species behmging to this genus are as follows : 

 Xyroea erythrophihuhiid (A\'ied) 

 Nyroca hnitnua Kyton 

 Xyroea natioui ( Sclater and Salvia) 

 Xyroea americana (Eyton) 

 Xyroea nymca (Giildenstadt) 

 Xyroea innotata Salvadori 

 Xyroea australis Eyton 

 yyroca bacri (Radde). 



'Philos. Zool., II, 1822, p. 260. 



-.N'liiiiciicl. aius. Ilciii. Oniitli., iSJtO. ii. :;4'i 



