90 
The erroneous estimates of the size of the world in the 
early centuries was compared to our own estimates of the 
solar parallax. The adoption of the mean degree of five 
hundred stadia implied neither carelessness nor ignorance. 
This is not the only correction required, but it is the only 
one necessary for the elucidation of the “bit of coast” 
under consideration. To deal with the general subject 
much more is required. This caution is necessary, as the 
numbers employed on the present occasion could not be 
generally applied alone. 
This is but a “ Chip from the Workshop.” The whole 
subject is preparing for publication. In the process of the 
work it has been found that the so-called blunders attri- 
buted to Ptolemy are, almost all of them, capable of satis- 
factory explanation when his modes of thought and work 
are understood. 
MICROSCOPICAL AND NATURAL HISTORY SECTION. 
December 3rd, 1877. 
A. Brothers, F.R.A.S., in the Chair. 
Mr. John Boyd exhibited specimens of the Chiego or 
“ Jigger” Flea (Pulex penetrans , L.) from Demerara, and 
explained its method of attacking the feet, thereby causing 
them to swell, and unless speedily extricated, being the 
means of danger, sometimes so great as to render amputa- 
tion necessary. Magnified representations of the mouth 
maxillary palpi, mandibles, and proboscis of this species 
and likewise those of P. irritans and P. felis were shown, 
and the various distinctions between the species pointed 
out. The maxillae are in P. penetrans quite rudimentary; 
and in other respects it is remarkable for its smallness, the 
size and strength of its lancets, and its peculiar habit of 
nidification. 
