Mr Macgiliivray on a new Species of Pccten. 167 
In a systematic arrangement, it would rank under the division, 
Auricula altera majori, margine infra-auriculari denticulato ; and 
might be characterised as follows : 
P. niveus orbicularis, fragilis, diaphanus, candidus, radiis 46, 
subcompressis,rotundatis, sparsim breviter tenuiterque echi- 
natis. It is represented in Plate III. Fig. 1. 
Art. XIX. — Remarks on Professor Hansteerds Account of a 
Shooting Star , seen in the Day-time. By Mr Thomas Dick 
of Perth. 
In the 24th Number of the 44 Edinburgh Philosophical Jour- 
nal,” p. 406. a notice is inserted of a phenomenon having been 
observed by M. Plansteen, when employed in measuring the ze- 
nith distances of the Pole Star. This phenomenon is described 
as 44 a luminous body, which passed over the field of the univer- 
sal instrument telescope ;” and the Professor concludes, that it 
must have been 65 a meteor,” or 46 shooting-star,” descending 
from the higher regions of the atmosphere ; and that this w r as 
44 perhaps the only instance in which a shooting star has been 
seen at mid-day, in clear sunshine.” 
That shooting stars may occasionally pass through the at- 
mosphere, in the day-time, as well as during the night, I do not 
mean to call in question ; but I have good reason for believing, 
that the phenomenon referred to, was a body of a very different 
description ; and perhaps the following statement may tend to 
confirm this opinion. 
About twelve years ago, I was engaged in a series of observa- 
tions on the celestial bodies, in the day-time, by means of an 
equatorial telescope, for the purpose of ascertaining what stars 
and planets may be most easily seen in the day-time ; what de- 
grees of magnifying power are requisite for distinguishing them ; 
how near their conjunction with the sun they may be seen; and 
whether a diminution of the aperture of the object-glass of the 
telescope, or an increase of magnifying power, has the greatest 
effect in rendering a star or a planet visible in day-light *. In 
* The results of these observations were published in Nicholson's Phil. Journ . 
for Oct. 1813; and several subsequent observations are noticed in the Edhu Phil 
Journ., No. V. p. 191., and No. XIII. for July 1822. 
