SIWALIK BIRDS. 
7—141 
impossible to say whether the fossil form, or forms, be not respectively identical 
with one or more of the living species. In view of the impossibility of distinguishing 
several of the Siwalik reptiles from existing species, it is not imj)robable that there 
may be a similar specific identity between some of the birds of the two epochs ; but 
our knowledge of the rate of specific evolution in the latter class is at present so 
imperfect that nothing can be advanced with any confidence. The writer has not 
seen a description of L. arvernensis ; which name is, however, of later date than L. 
falconei'i. Under these circumstances the name Leptoptilus falconeri must be regarded 
as a purely provisional one. The above-mentioned humerus from Pikermi indicates 
a bird considerably smaller than L. aipala. 
Distribution. — Remains of the present form have been obtained from the typical 
Siwalik Hills, and the Punjab. 
Genus, non. det. 
History. — The specimen forming the subject of the present notice was previously 
referred to Leptoptilus falconeri.^ 
Cervical vertebra. — In plate XIV., figs. 7, 7a, 7b, 7c, 7d, there are given five 
views of the cervical vertebra of a large bird collected by Mr. Theobald from the 
Siwaliks of Asnot, Punjab. The specimen is a fourth cervical ; so determined from 
the large size and shortness of the neural spine (w5., fig. 7c), and the shortness of 
the lateral carotid canaP (cr., fig. 7). The summit of the neural spine and the 
processes surrounding the carotid canals have been broken away. The bone, 
although rather larger, has such a general agreement in structure with the cor- 
responding vertebra of Leptoptilus argala, that it may be pretty safely referred either 
to the Ciconiidce or the allied Ardeidae. 
Compared with the fourth cervical of Jjeptoptilus argala the specimen differs by 
being shorter and higher ; by the more distinct hollow (.r, fig. 7c) between the 
prezygapophyses [prz.) ; by the larger size of the neural spine {ns.), which extends 
backwards over the postzygapophyses {ptz.)] by the closer approximation of the 
two latter ; and by the absence of distinct surfaces for muscular attachment above 
the same. In its greater vertical height and longer neural spine the vertebra of L. 
crumeniferus comes nearer to the fossil ; but is distinguished by the other characters 
of that of L. argala. In both the existing species the prezygapophyses {prz.) are 
separated by a distinct notch, extending as far backwards as their posterior border. 
The fossil bone, although much larger, agrees more nearly in proportions with 
the fourth cervical of Balceniceps and Mycteria, but is distinguished by the neural 
spine extending farther backwards, and being higher posteriorly, as well as by the 
more distinct hollow {x) between the prezygapophyses. It is on the whole nearer to 
Mycteria than Balceniceps. Compared with the fourth cervical of Cancroma {Ardeidcc) 
the Siwalik bone is of very much larger size, but agrees in its relatively large height, 
1 ‘ Records,’ vol. XII., p. 56. 
2 Two carotids are present in the Ciconiidce and most of the Ardeidcc ; vide Garrod, ‘ Proc. Zool Soc.,’ 1873, p. 467. 
