CANCEOMA. 185 



Fam. CANCEOMID^l. 



Dr. Sharpe considers the Boatbills to be an exaggerated form of Night-Heron, but 

 we prefer to follow Mr. Ridgway in recognizing them as a distinct family of the 

 Herodiones. The possession of four pairs of powder-down tracts, and the remarkable 

 beak, from which the Boatbills gain their name, are sufficient to distinguish them 

 from any of the Heron-like birds, though, as regards this latter feature, they bear 

 some resemblance to the African Whale-headed Stork {Balceniceps), which, besides 

 differing in many osteological characters, is distinguished by its much larger size and 

 more sombre plumage. 



The family contains but a single genus. 



CANCROMA. 



Cancroma, Linn. Syst. Nat. i. p. 233 (1766); Ridgw. Bull. U. S. Geol. & Geogr. Surv. ii. p. 220 

 (1878) ; Sharpe, Cat. Birds Brit. Mus. xxvi. p. 163 (1898). 



This genus contains but two species — one the Common Boatbill of South America, 

 C. cochlearia, and the other its Central-American representative, C. zeledoni. 



1. Cancroma zeledoni. 



Cancroma cochlearia (nee Linn.), Scl. P. Z. S. 1857, pp. 306 \ 230 " ; 1859, p. 369 ' ; Sol. & Salv. 



Ibis, 1859, p. 227^; Salv. Ibis, 1864, p. 387 ^ P. Z. S. 1870, p. 218'; Ibis, 1889, p. 376' ; 



Lawr. Ann. Lye. N. Y. vii. p. 478'; ix. p. 142 '; Mem. Bost. Soe. N. H. ii. p. 310"; Bull. 



U. S. Nat. Mus. no. 4. p. 48 " ; v. Prantz, J. f. Orn. 1869, p. 376 " ; Finsch, Abhandl. nat. 



Ver. Bremen, 1870, p. 358 " ; Sumichr. La Nat. v. p. 233 '*; Nutting, Pr. U. S. Nat. Mus. 



V. p. 406 '' ; vi. p. 396 '' ; Boucard, P. Z. S. 1883, p. 458 '\ 

 Cancroma zeledoni, Ridgw. Pr. U. S.'Nat. Mus. viii. p. 93"; Zeled. An. Mus. Nac. Costa Rica, 



1887, p. 130 " ; Sharpe, Cat. Birds Brit. Mus. xxvi. p. 165 '°. 

 Cochlearius zeledoni, Stejn. Stand. Nat. Hist. iv. p. 178 " ; Ferrari-Perez, Pr. U. S. Nat. Mus ix. 



p. 171 " ; Richm. Pr. U. S. Nat. Mus. xvi. p. 527"; Chapm. Pr. U. S. Nat. Mus. xviii. 



p. 697 '' ; Bangs, Pr. New Engl. Zool. Club, ii. p. 15 ", 



Supra clare cinerea, remigibus rectricibusqne margaritaceo-cinereis, primariis extus clarioribus ; pileo, valde 

 cristato, nigro ; fronte ciaerascenti-alba ; facie laterali grisescenti-vinacea ; gula nuda, gutture imo 

 albicante ; prsepectore et peetore summo pallide vinaceo-brunneis ; pectore reJiquo cum abdomine et 

 subcaudaUbiis satnratioribus, vinaceo-castaneis ; corporis lateribus cum axiUaribus et subalaribus 

 interioribus nigris ; subalaribus externis et remigibus infra pallide cinereis ; jnargine alari albo : rostro 

 nigro ; pedibus dilute viridibus ; iride nigra. Long, tota circa IT'O, alae 10'7, caudae 4*0, culm. 3-0 

 tarsi 2-8. (Descr. maris adulti ex Momotombo, Nicaragua. Mus. nostr.) 



2 mari aimilis, sed saturatior, plumbescens, gutture imo et prsepectore magis cinnamomeis, schistaceo lavatis. 

 Long, tota circa 17"0, alae ll'O. (Descr. feminae adultae ex Vina de Chorcba, Panama. Mus. nostr.) 



Juv. Brunneseens, plus minusve schistaceo adumbrata ; remigibus rectricibusque clare schistaceis ; pileo 

 panllo cristato, nigro ; fronte schistacea ; corpore subtus pallide cineraceo, vix vinaceo lavato, plumis 

 medialiter albido striatis. (Descr. av. juv. ex Atoyac, Mexico. Mus. nostr.) 



BIOL. CENTE.-AMER., Aves, Vol. III., December 1901. 21 



