560 C. La-pivorth — On British GraptoUtes. 



(The genera Nos. 14, 15, 16, 17, and 27 of the Table have never 

 been met with in S. Scotland, and are as yet without distinctive 

 titles.) 



NOTES. 



(1). Primordial Buds. 



The term " bud" is employed throughout this paper merely as a 

 concise and at the same time convenient designation for the small, 

 primary, lateral tubercle, from which the polypiferous branch is 

 ultimately developed. This application of the term is open to some 

 objection, as it appears, by implication, to include the theory that it 

 is possible for the coenosarc of the sicula to push out lateral buds 

 through a dense continuous sheathing of chitine. Nevertheless, 

 while it is impossible to find any other term which so exactly ex- 

 presses what a2:)pears to be the mode of development in such forms as 

 Nemagraptus, yet the designation is intended to be rather expressive 

 of the appearance than of the fact. What that fact is supposed to 

 be will be explained elsewhere. 



(2). '• Angle of divergence." 



Two distinct angles of divergence are made by the opening of the 

 principal branches in every bilateral polypary. They are the ventral 

 or polypiferous angle, and the dorsal or nonpolypiferous angle. The 

 latter is invariably bisected by the persistent sicula. I have there- 

 fore termed it the " sicular angle " in the former portion of this 

 paper. This has been done merely as a matter of convenience, in 

 order to bring into relief the relations that exist between the opening 

 of the branches and the direction of the persistent sicula ; and also 

 ultimate relations of the latter to the proximal extremity of the 

 adult polypary.^ Strictly sj)eaking, I would suggest that the term 

 "angle of divergence" be in all cases restricted to the "distal angle" 

 or that made by the opening of the branches on the side of the axil 

 remote from the proximal extremity of the polypary. 



(3). I have only become acquainted within the last month with the 

 character of Herr Eichter's latest researches among the GrcqjtolitidcB. 

 I have as yet been unable to procure his recent paj)er, and my 

 only source of information on the subject is Prof. Allman's de- 

 scriptive note in the Second Part of the Monograph of the Tubula- 

 rian Hydroids (p. 185). I have therefore omitted all reference to his 

 conclusions in the. body of this paper. I hope to be able to do full 

 justice to his original observations when I have been afforded an 

 opportunity of perusing his remarkable memoir. 



The assistance afforded me by the published views of Mr. Hop- 

 kinson and Professor Nicholson have been already alluded to. I 

 have also to thank Professor Allman for the kindly expression of his 

 opinions on some of the more doubtful points. 



The Geological Distribution of the Graptolites will be treated of 

 in a separate pajDcr. 



' The reference to the mode of growth in Fhijllograptus, p. 502, is probably an 

 error, and should be deleted. 



