ACADEMY OF NATURAL SCIENCES. 353 



Mr. Stearns presented, in behalf of Mr. Rowell, the following 

 description of a new species of Pisidium, collected during the 

 field excursion to Angel Island : 



Description of a New Species of Pisidium. 



BY J. ROWELL. 



Pisidium angelicum, Rowell. 



Shell rounded oval, nearly equilateral, very convex ; margin well rounded ; 

 beaks very slightly raised and very approximate ; surface subgranulate, marked 

 with from one to six very decided striae or lines of growth ; teeth too minute 

 for observation. 



Long, (of largest) 2 mill., Lat. 1.5 mill. ; Diam. 1 mill. 



Habitat: Angel Island. 



Of California species, it is most like P. abditum, but differs in its sculpture, 

 its less prominent beaks and its more globular and equilateral form. Most 

 specimens are covered by an exceedingly persistent coat of jet black mud, mak- 

 ing examination of them very difficult ; but some are perfectly clean. 



Mr. Stearns read the following note upon a recent 



Exhibition of Parhelia. 



On Wednesday, the 17th day of (April) last month, at about 5 o'clock in the 

 afternoon, my attention was attracted towards the heavens by an exhibition of 

 the rather unusual phenomena (unusual in this latitude) known as Parhelia. 



The sky in the west at the time was somewhat cloudy, and the atmosphere 

 hazy. I was unable to determine the exact position of the sun, but its altitude 

 was approximately 22° above the horizon ; the diameter of the circle or halo 

 was about 24°. A horizontal line, drawn through the sun and projected suffi- 

 ciently in a northerly and southerly direction to intersect the halo, displayed at 

 each point of intersection, a parhelion or mock sun of very considerable bril- 

 liancy, and continued for upwards of half an hour. 



A much more extensive display of these phenomena was witnessed by me in 

 the month of April, 1858, while residing near Boston, Massachusetts. 



The sun was not far from the zenith, surrounded by a single broad halo, 

 which latter was in turn inclosed by an outer circle of many halos all intersect- 

 ing with each other and with the central halo — each of the numerous points 

 of intersection gemmed with a parhelion. So extensive was the display, owing 

 to the number of halos and the attendant parhelia, that the whole heavens from 

 the zenith to within apparently 30° of the horizon, seemed covered with brilliant 

 circles or rings, and resplendent with numberless suns. The sky, at the time, 

 was obscured by a haze of considerable density, and a chilling wind was blowing 

 from the south. 



