200 



P.flabellata,Tenison Woods, of our own coast, than to P, laticos- 

 tatus, Quo^j, of New Zealand. The latter differs from P. M'Goyi 

 in being much more solid, and in having invariably 10 more 

 ribs ; the length also, generally exceeds the breadth and the con- 

 vexity is greater than P. M'Coyi towards margin. With P. 

 flahellata, Tenison Woods, it differs in being less solid and in 

 having invariably 7 more ribs ; P. flahellata having invariably 

 24. The teeth on the latter are generally 10 as in P. M'Coyi, 

 and in this respect and in ligamental area show a closer cor- 

 respondence with the latter than with P. laticostatus. P. 

 flahellata, in Tasmania, moreover, is invariably exactly as broad 

 as it is long. It would appear therefore that the characteristic 

 shell of Table Cape is not identical with living species, and 

 that it seems to be an intermediate form between P. flahellata, 

 Tenison Woods, and P. laticostatus, Quoy, although showing 

 a closer alliance with the former. 



From the appearance of the fossil P. laticostatus, figured 

 (PI. xix., Decade ii.) by Professor M'Coy, and from the cir- 

 cumstance that all the Australian fossil forms examined by me 

 are identical with the Table Cape form, it appears to me to 

 be doubtful whether, on closer examination, the bird rock 

 form referred to by Professor M'Coy will prove to be identical 

 with the living P. laticostatus, Quoy, in all respects. This 

 however can be easilv set at rest. 



NOTES OF SPECTROSCOPIC OBSERVE ATIONS OF 

 COMET " PONS," 27th JANUARY to 2nd FEB- 

 RUARY, 1884. 



By a. B. Biggs. 



[Read April 8, 1884.] 



The spectroscope used was a small direct- vision compound 

 prism by Browning, the telescope being a refractor of 3-inch 

 aperture. After some difficulty in getting the object focussed 

 upon the slit of the spectroscope there flashed out three 

 bright bands. They appeared somewhat pyramidal in form, 

 the base being on the south side of the telescopic image. 

 The relative spaces between them I judged to be about as 

 2 to 3. I could not distinguish any difference, or even any 

 trace, of colour ; they appeared rather to resemble a phos- 

 phorescent glow. I had not the means, at the time, of 

 determining their relative positions in the spectrum. On 

 subsequent evenings, however, I took every precaution for 

 determining this point. 



