PROFESSOR DICKSON ON SOME ABNORMAL CONES OF PINTTS PINASTER. 509 



III. P. Pinaster— MrnvkousQ— (Plate XX. figs. 4 and 5 ; Plate XXII. 

 tig. 1). Length of cone 3-| inches. Some scales on one side are somewhat 

 damaged, by having been bitten, apparently before the cone was mature. The 

 lower third of this cone exhibits a left-handed trijugate of the ordinary sys- 

 tem, with secondary spirals 6 D, 9 S, 15 D, 24 S, and whose three fundamental 



spirals have each the divergence — — - Two of six spirals to the right 



Lo X o 



" converge " into one, producing in the middle third of the cone the arrangement 

 5 D, 9 S, 14 D, 23 S, = a right-handed — spiral (series -, - -, _,_,—, &c). 



In the upper third of the cone, we have two further changes : in the first place, 

 two of the nine spirals to the left " converge " into one, giving the arrange- 

 ment 5 D, 8 S, 13 D, = a left-handed spiral of the ordinary series, probably 



13 



— ; and then, a little higher up, two consecutive scales of one of the spirals 



by 5 to the right (adjacent scales of two of the spirals by 8 to the left) have 

 partially coalesced, almost precisely in the same way as the two scales near 

 the top of the last cone, giving beyond that, up to the top of the cone, 



the arrangement 5 D, 7 S, 12 D, = a right-handed spiral of the series 

 12 3 5 8,, , , , 13 



2'5'fT2'T9' &C -' pr ° bably SI" 



The changes in this very complicated cone are shown in the following 



table : — 



Table C. — Cone of P. Pinaster. 





S 



D 



S 



D 



S 



D 



S 



V 



13 

 "31 



Top, 



— 



1 



2 



5 



7 



12 



19 



31 = 



Below Top, 



1 



2 



3 



5 



8 



13 



21 



34 = 



13 

 34 



Middle, 



— 



1 



4 



5 



9 



14 



23 



37 = 



8 

 "37 



Bottom, 



— 



— 



3 



6 



9 



15 



24 



39 =- 



5 



13x3 



IV. P. Pinaster— Muirhouse— (Plate XX. figs. 6 and 7; Plate XXII. fig. 



2). Length 4^ inches. In this cone, nine secondary spirals to the left run 



continuously from near the bottom to the top. At the very bottom, there is a 



considerable amount of irregularity, some of the scales being of exceptional 



size and shape. It is probable, however, that were it not for the mal-develop- 



7 

 ment, the arrangement here would be a — spiral, similar to what we meet 



further up on the same cone. However this may be, a " divergence " distinctly 

 takes place of one secondary spiral into two, which form members of a set of 

 eight running to the right. Thus the first arrangement which we can legitimately 



VOL. XXVI. PART II. 6 R 



