﻿Vol. 66.~\ EVOLUTION OF ZAPHRENTIS DELANOUEI. 533 



•collected many years ago by the late Mr. James Bermie, of the 

 Geological Survey of Scotland. 



I am indebted to Mr. James Xeilson for his kind permission to 

 cut several specimens from Campsie and Orchard, in his well-known 

 collection. 



Dr. Home has granted every possible facility during the progress 

 of the work, and I owe him my sincere thanks for his continued 

 encouragement. To other colleagues of mine I am indebted for 

 much advice and assistance ; while Mr. Macconochie's invaluable 

 discovery of the Liddesdale delanouei-beds is deserving of especial 

 mention. 



VI. Specific Descriptions. 



The parent species, Zaphrentis delanouei, has been fully described 

 elsewhere (Geol. Mag. 1908, pp. 63 et seqq. & pi. v, figs. 5-7) ; 

 but as the characters are preserved in a more or less modified form 

 throughout the gens, a condensed diagnosis is appended as a basis 

 for notes on the new species. 



Zaphrentis delanouei, M.-Ed. & H. (PI. XXXVII, figs. 3 a-3 c) 



(For synonymy, see Greol. Mag. loc. sujyra cit.) 



Corallum conical or slightly curved. The epitheca has 

 well-marked longitudinal ribbing. 



The major septa are stout, thickened at the inner end, and 

 have a characteristic curvature convex to the cardinal fossula, 

 which is situated on the concave side of the corallum, and in trans- 

 verse section is large and widely expanded at the inner end. 



Minor septa quite rudimentary. 



Average dimensions of adult : height = 2*5 cm. ; diameter of 

 calicinal rim = 1*3 cm. ; number of major septa to above diameter 

 of calyx, 27 ; depth of calyx = 1 cm. 



Tabulae 1 to 2 mm. apart, arched in the centre and strongly 

 depressed into the cardinal fossula. 



Zaphrentis parallela, sp. nov. (PI. XXXVII, figs. 4 a-4 d.) 



All characters as in Z. delanouei, except that, in transverse 

 sections, the ephebic cardinal fossula is parallel-sided, or even 

 slightly constricted towards the inner end ; in the neanic stage 

 the typical expanded delanouei outline is usually, but not neces- 

 sarily, seen. 



Zaphrentis lawstonensis, sp. nov. (PL XXXVII, figs. 9-10 c.) 



Corallum small, of a more narrow cono-cylindrical form than 

 other members of the gens, and often exhibiting strong concentric 

 rugse ; wall usually very thick. 



Average dimensions: height = 10 to 20 mm. ; diameter=4'5 

 mm. ; depth of calyx =5 mm. 



Major septa usually very thin ; the cardinal fossula is 

 constricted at the inner end, although not to such an extent as in 

 Z. constricta (see below, p. 534). 



