74 DICTIONARY OF BIRDS 
divided the Class Aves into two Subclasses, to which he applied the names 
of Insessores and Grallatores (hitherto used by their inventors Vigors and 
Illiger in a different sense), in the latter work relying chiefly for this 
division on characters which had not before been used by any systematist, 
namely, that in the former group Monogamy generally prevailed and the 
helpless nestlings were fed by their parents, while the latter group were 
mostly Polygamous, and the chicks at birth were active and capable of 
feeding themselves. This method, which in process of time was dignified 
by the title of a Physiological Arrangement, was insisted upon with more 
or less pertinacity by the author throughout a long series of publications, 
some of them separate books, some of them contributed to the memoirs 
issued by many scientific bodies of various European countries, ceasing only 
at his death, which in July 1857 found him occupied upon the unfinished 
Conspectus Generum Avium before mentioned. In the course of this series, 
however, he saw fit to alter the name of his two Subclasses, since those 
which he at first adopted were open to a variety of meanings, and in a 
communication to the French Academy of Sciences in 1853 (Comptes 
Rendus, xxxvii, pp. 641-647) the denomination Jnsessores was changed to 
Altrices, and Grallatores to Precoces—the terms now preferred by him 
being taken from Sundevall’s treatise of 1835 already mentioned. The 
views of Bonaparte were, it appears, also shared by an ornithological 
amateur of some distinction, Hogg, who propounded a scheme which, as 
he subsequently stated (Zool. 1850, p. 2797), was founded strictly in 
accordance with them; but it would seem that, allowing his convictions 
to be warped by other considerations, he abandoned the original 
“physiological” basis of his system, so that this, when published in 1846 
(Edinb. N. Philos, Journ. xli, pp. 50-71) was found to be established on a 
single character of the feet only, whereon he defined his Subclasses Con- 
strictipedes and Inconstrictipedes. 'The numerous errors made in his asser- 
tion hardly need pointing out. Yet the idea of a ‘‘ physiological” arrange- 
ment on the same kind of principle found another follower, or, as he thought, 
inventor, in Newman, who published (Proc. Zool. Soc. 1850, pp. 46-48, 
and Zool. pp. 2780-2782) a plan based on exactly the same considerations, 
dividing Birds into two groups, ‘‘ Hesthogenous ”—a word so vicious in 
formation as to be incapable of amendment, but intended to signify those 
that were hatched with a clothing of down—and “ Gymnogenous,” or 
those that were hatched naked. These three systems are essentially 
identical ; but, plausible as they may be at the first aspect, they have 
been found to be practically useless, though such of their characters as their 
upholders have advanced with truth deserve attention, and, as will be seen 
in the present work, Dr. Gadow’s terms Nidicole and Nidifugx, used in no 
systematic sense, express with greater accuracy what is needed, Physiology 
may one day very likely assist the systematist ; but it must be real 
physiology and not a sham. : 
In 1856 Prof. Gervais, who had already contributed to the Zoologie 
of M. de Castelnau’s Expédition dans les parties centrales de Amérique du 
Sud some important memoirs describing the anatomy of the Hoacrzin 
(page 421) and certain other Birds of doubtful or anomalous position, 
published some remarks on the characters which could be drawn from the 
