SHEA TlI-IilLLS. 



93 



Fio. 40. — Uuad of Chicmis alba, white shcatb-btU. 



southern hemispberc, tlicy being cliieflj' found on tlic islands adjacent to tiio southern 

 extremity of South Anieriea, — Kergueleu's Island and the t'ro7,els. 



The most reinarkablc and quite uiruiue structure of these birds is thesaddle-sliaj)e(l 

 horny sheath, overlying the base of the eulmen and partly concealing the nostrils, — 

 hence the name sheath-bill. This sheath is continued backward into a kind of hood 

 covering the face, being naked and caruiiculated on the lores and ocular region, liut 

 densely feathered on the forehead, as represented in the accompanying cut. The bill 

 and the naked skin are yellowish in CVtiom's «^6a, black in C7(. miHor, the latter also dif- 

 fering considerably in the shape of the sheath. On the carpus is a knob-shaped ])romi- 

 nenee which sujiports a wing spur. The plumage of both s]iecies is dazzlingly white all 

 over. The feet :ive covered with a reticulate skin, both in front and behind ; four 

 toes are ])resent, having the normal 

 number of phalanges, which diminish in 

 size from the basal to the ti'rmiiial one, 

 only very small webs connecting the an- 

 terior toes at the base. 



The hal)its of Ch. minor, which in- 

 habits Kerguelen's Island and the Cro- 

 zets, — unless the bird of the latter, which 

 seems to have darker legs, is a sejiarable \''\n' 

 form, — have been only very recently in- 

 vestigated, and specimens are still very 

 rare in collections. The recent Ameri- 

 can, English, and German Transit-of-Venus expeditions to that desolate shore have 

 furnished us with excellent descriptions of the manners and peculiarities of that 

 species. All observers agree as to their resemblance in a])jiearance, manner of 

 caressing one another, gait and flight, to ])igcons or ptarmigans. Dr. Kidder saw 

 them eat only soft, green seaweed when in the wild state, but Mr. Eaton, of tlie 

 English party, asserts that they also feed on mussels and isopod Crustacea, and that 

 they greedily devour shags' and penguins' eggs. The former observer enlarges u])i)n 

 their great tameness and curiosity. They nest in holes between or behind rocks, laying 

 one to three eggs, which somewhat resemble those of the oyster-catcher, toward the 

 end of December and the beginning of January. The chicks are covered with a uni- 

 form slate-gray down. Males and females are alike, but the loral caruncle is smaller 

 in the latter, which also has the carpal spine smaller and flesh-colored, and not black 

 as has the male. The young birds are like the adults, but have i)ink tii)s to their 

 wings. 



The TiiiKOCOKiD.E, a faiuily consisting of two genera, Thiiioconis and Attai/is, with 

 together a little more than half a dozen species, inhabit South America down tu 

 Magelliaen's Strait and the Falkland Islands; in the tropical ])ortions they occur, iiow- 

 ever, oidy in the elevated regions. Externally they resemble, in size and color, ipiails 

 or partridges, the analogy being carried so far as to also embrace the shortness of the 

 legs, but tlie long and pointed wings, with the long secondaries, at once suggest their 

 affinity with the Scolopacoid birds. At first they were regarded as tJalliuaccoiis binls, 

 while some authors referred them to the ])igeons or sand-grouse ; but the Liniicoliiie 

 pterylosis and the many obvious structural charactei-s soon secured place for tlicin 

 among the Grallai. Finally, Professor Garrod, in 1874, settled the question beyond 

 dispute, by giving an account of all their anatomical characteristics. From his iuves- 



