232 W. G. RTDEWOOD. 



oral lamella are more prominent as free flaps than in C. 

 hodgsoni. 



Pinnules first appear in the stage represented in j, i. e. in 

 the stage when the fourth plumes are appearing, or possibly 

 a little earlier (h). They are at first confined to the first 

 pail- of plumes, and they appear as five or six pairs of small 

 eminences arising simultaneously ; additional pairs develop 

 in succession at the basal end of the series. In k there are 

 seven pairs, and in L eleven or twelve pairs of pinnules on 

 the plumes of the first pair. The pinnules on the second, 

 third, and subsequent plumes arise later than those on the 

 first, as might be expected. About four pairs of pinnules 

 are just appearing on the second plumes in J. 



Masterman,^ in figuring a bud about as advanced as g and 

 H of text-fig. 4 of this paper, shows four pairs of long slender 

 pinnules on the first plumes. There is nothing comparable 

 with this in my preparations. My observations also fail to 

 accord with those of Dr. Masterman in the matter of the 

 development of the first few pinnules on the plumes. In 

 figs. 69 — 74 of his Plate 4 he gives figures illustrating the 

 growth of a plume — he does not say which. In fig. 71 there 

 are no pinnules, in fig. 72 one pair, in fig. 73 the first pair 

 have elongated considerably, and there is a new pair on their 

 proximal side, in fig. 74 there are four pairs of pinnules 

 shown. My own observations go to show that the first five 

 or six pairs of pinnules arise simultaneously on the first 

 plumes; on the second and third plumes the first four or five 

 arise simultaneously, and on the fourth pair (text-fig. 4, k, 4) 

 the first three or four. At a stage when any one plume has 

 but four pairs of pinnules I have not seen the pinnules nearly 

 so long and slender as those shown in Masterman's fig. 74. 



In L of text-fig. 4 the fifth plumes have attained consider- 

 able size and exhibit about four pairs of pinnules. The pin- 

 nules on the first and second plumes are now long, except the 

 youngest of the series near the base of the plume-axis. End- 

 bulbs with refractive beads {r.h.) are present on the first four 

 ' 'Trans. Roy. Soc. Edin.,' vol. xxxix, 1898, pi. 2, fig. 24. 



