STEREORNITHES 905 
remains, mostly of gigantic size, found in the Tertiary strata of Santa 
Cruzin Patagonia. They were considered to combine the.characters 
of Anseres, Herodiones and Accipitres, to shew a transition from the 
Anatidx to the Vulturidz, and to be separable into nine genera, which 
were grouped in four Families: In a critical review of this memoir, 
published in the same year, Dr. Florentino Ameghino (fevist. Argent. 
Hist. Nat. i. pp. 441-453) came to the conclusion that the whole 
series of remains might be referred to two genera, Phororhacos! and 
Brontornis, both included in the family Phororhacidx, which he placed 
among the Jtatitz, a third genus, named Opisthodactylus from a 
peculiarity in the position of the facet for the hallux, being at the 
same time proposed. These views were provisionally accepted by 
the present writer (/bis, 1893, pp. 40-47) ;-but an examination of 
the specimens in the Museum of La Plata induced him (Nat. Sc. 
1894, p. 125) to consider the retention of the Order Stercornithes 
desirable, and also to declare that the Santa Cruz beds were in all 
probability not older than the Upper Oligocene ; while here it may 
be mentioned that the group of Birds is also represented in the 
somewhat newer deposits of Monte Hermoso near Bahia Blanca. 
The most important information regarding these Birds is that given 
in 1895 by Dr. Ameghino (Bole. del Inst. Geograf. Argent. xv. 11, 
12), where a considerable number of their remains, obtained by his 
brother in Patagonia, are figured ; the validity of the group Stereor- 
nithes is admitted, and nine genera” are referred to it, Phororhacos 
with six species, Pelecyornis with three, Brontornis with one or two, 
and the others with one each; all but Opisthodactylus, which is 
regarded as forming a distinct Family, being grouped as Phororhacide. 
The most conspicuous peculiarity of the Séereornithes is the 
enormous size and ponderous structure of the skull, which is quite 
unlike that of any recent Bird, and seems out of all proportion to 
the limbs, gigantic as are some of the leg-bones. ‘The upper jaw is 
remarkable for its extreme lateral compression, and yet is of great 
depth, its extremity terminating in a hook, while that of the man: 
dible turns upward There is no ossified interorbital septum, and 
the orbits apparently communicate with the preorbital vacuity, 
while the nostrils, which are situated high up, are pervious. The 
1 This, with the spelling Phorysrhacos, had been originally described in 1887 
by Dr. Ameghino (Bolet. Mus. de la Plata, i. p. 24) from its mandible as an 
Edentate Mammal ; but its ornithic nature was declared by him four years later 
(Revist. Argent. Hist. Nat. i. p. 255). As to the etymology of the name, con- 
jecture only can be entertained. That which is next to it in point of time is 
Mesembriornis, Moreno (Progresos del Mus. la Plata, p. 29. Buenos Aires: 1889.) 
2 These are by no means the same as the nine before proposed by Sefiores 
Moreno and Mercerat, all but two of which are submerged, while others are 
proposed. 
’ 8 Sefiores Moreno and Mercerat figured the mandibles as upper jaws (op. cit. 
pls. v. fig. 3, vi. fig. 2, viii. fig. 4, ix. fig. 2, pp. 20, 21). 
