260 PROFESSOR OWEN ON CNEMIORNIS. 
mandible and the fronto-lacrymal apex of the cranium, and in the spheno-mastoid bridge 
crossing the tympanic cavity, Cereopsis agrees with Cnemiornis. 
§ 3. Vertebre. 
Of the cervical vertebrae of Cnemiornis I have now as many as exemplify the usual 
modifications of their size, shape, and processes in this part of the spinal column of 
birds, also the general characteristics of such part in Lamellirostrals by a number of 
vertebre above the average in the feathered class; but the precise sum of cervicals 
waits a better opportunity of obtaining the skeleton of the same individual than has 
hitherto offered, and one knowingly availed of’. 
The main modification of the cervicals of Cnemiornis, as compared with those of other 
Natatores, is the greater extent of ossification of the neural arch. The parial hyp- 
apophyses also converge in the eleventh cervical to contact at their free ends; and those 
in the twelfth cervical have coalesced to form a complete inferior bony arch or ring.- 
This structure I have not observed in any other Anserine or Lamellirostral species’. 
Both characteristics of Cnemiornis are shown in the figures of the cervical vertebre 
in my first Monograph on the genus. The views chosen for this purpose gave, accord- 
ingly, the upper’, the under *, with the fore® and hind®, surfaces of the vertebre. In 
the present paper I therefore give a side view (Pl. XXXVI. fig. 6), and, for comparison 
with fig. 4, pl. 63, Trans. Zool. Soc. vol. y., a corresponding view of the homologous 
cervical in Cereopsis (ib. fig. 7) and Tachyeres (fig. 8). 
The cervical vertebre in Anserines, which have a single hypapophysis at the hind 
part of the centrum, beneath the hind articular surface, are the two or three which 
follow the axis. After a certain number without lower processes a pair of prehypapo- 
physes (Pl. XXXVI. figs. 7 & 8, ph) begin to project from beneath the costal arch, 
approach each other in succeeding vertebre without coalescing, and gain the under 
surface of the centrum as they lengthen. They then usually abruptly cease, and are 
replaced by a single hypapophysis at the middle of the fore half of the centrum; and 
this is continued, usually with decreasing length or suppression, to the dorsal series, 
where, after the first, the hypapophysis reappears with increased length. 
The cervical vertebra of Cnemiornis the subject of figs. 1-4, pl. 63 (tom. cit.), 
answers by the position of its hypapophysis to the third or fourth cervical in Cereopsis 
and Tachyeres. My present series shows it to be the fourth, and also includes the third 
cervical, of which I give a side view in P]. XXXVI. fig. 1, with a similar view of the 
homologous vertebra in Cereopsis (ib. fig. 2) and Tachyeres (ib. fig. 4). 
' Twelve cervical vertebra were collected by the Hon. Capt. Frazer in the Earnscleugh Caye, and are attri- 
buted to the same individual bird by Dr. Hector. 
* Tt oceurs in other groups of Aves; the illustration in my ‘ Anatomy of Vertebrates,’ vol. ii. p. 40, fig. 25, 
is from a Pelican. 
* Trans. Zool. Soe. vol. y. pl. 63. fig. 3. * Th. ib. fig. 4. STbyabitige ws ° Ib. ib. fig. 2. 
