CANCROMA. 185 
Fam. CANCROMIDZ. 
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 (Baleniceps), 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 (nec Linn.), Scl. P. Z.S. 1857, pp. 206'*, 2307; 1859, p. 869°; Scl. & Salv. 
Ibis, 1859, p. 227‘; Salv. Ibis, 1864, p. 387°; P. Z. 8. 1870, p. 218°; Ibis, 1889, p. 376'; 
Lawr. Ann. Lye. N. Y. vii. p. 478°; ix. p. 142°; Mem. Bost. Soc. N. H. ii. p. 310"; Bull. 
U.S. Nat. Mus. no. 4, p. 48”; v. Frantz. 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 7. 
Cancroma zeledont, 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. 1787; 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 rectricibusque margaritaceo-cinereis, primariis extus clarioribus ; pileo, valde 
cristato, nigro; fronte cinerascenti-alba; facie laterali grisescenti-vinacea; gula nuda, gutture imo 
albicante ; preepectore et pectore summo pallide vinaceo-brunneis; pectore reliquo cum abdomine et 
subcaudalibus saturatioribus, vinaceo-castaneis; corporis lateribus cum axillaribus et subalaribus 
interioribus nigris; subalaribus externis et remigibus infra pallide cinereis ; margine alari albo: rostro 
nigro; pedibus dilute viridibus; iride nigra. Long. tota circa 17:0, ale 10°7, caude 4:0, culm. 3-0, 
tarsi 2°8. (Deser. maris adulti ex Momotombo, Nicaragua. Mus. nostr.) 
mari similis, sed saturatior, plumbescens, gutture imo et prepectore magis cinnamomeis, schistaceo lavatis. 
Long. tota circa 17:0, ale 11:0. (Descr. femine adultz ex Vina de Chorcha, Panama. Mus, nostr. ) 
Juv. Brunnescens, plus minusve schistaceo adumbrata; remigibus rectricibusque clare schistaceis ; pileo 
paullo cristato, nigro; fronte schistacea ; corpore subtus pallide cineraceo, vix vinaceo lavato, plumis 
medialiter albido striatis. (Deser. av. juv. ex Atoyac, Mexico. Mus. nostr.) 
BIOL. CENTR.-AMER., Aves, Vol. III., December 1901. 24 
