﻿534 MR. R. G. CARRUTHERS ON THE [Nov. I9IO, 



The species is included in the gens of Zaphrentis delanouei, since 

 it possesses the following characters in common with all members 

 of the gens : — 



(1) Strong longitudinal ribbing on the epitheca. 



(2) Cardinal fossula on the con«ave side of the corallum. 



(3) Curvature of septa convex to the cardinal fossula. 



(4) Tabulae of the same nature and spacing as in other members of the 



gens. 



Nevertheless, the septa are usually much thinner than in other 

 members of the gens, and they are not markedly thickened at their 

 inner ends. 



The species is entirely unknown from higher beds. Neither 

 can it be said that any of the higher mutations pass through a. 

 laivstonensis stage in neanic life, if the very thin septa usually 

 found in the latter species be regarded as an essential character ; 

 but many specimens of the pre-existing form, Z. paraXlela, do 

 develop very thin septa in their late ephebic stages. 



All these facts, therefore, point to Zaphrentis luwstonensis as a 

 short-lived side-branch from the direct line of evolution. 



Zaphrentis constricta, sp. nov. (PI. XXXVII, figs. 5a-5 d.) 



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

 sections the ephebic cardinal fossula is strongly constricted at the 

 inner end; in neanic life the fossula is usually of the parallela 

 type, although, in a few cases, probably of advanced forms, the 

 characteristic constricted outline is assumed at a very early stage. 



It is possible that this species may be synonymous with Thomson's 

 Zaphrentis pachy septa (see Proc. Phil. Soc. Glasgow, vol. xiii, 1881 t 

 pi. iv, fig. 9). I examined his type in the Kilmarnock Museum,. 

 but was unable, from the one section available, to satisfy myself 

 as to its relation to Z. constricta. Since then practically the 

 whole of Thomson's magnificent collection has been destroyed by 

 fire — an irreparable loss to Scottish palaeontology. 



Zaphrentis disjuncta, sp. nov. (PI. XXXVII, figs. 6 a-8 d.) 



Zaphrentis cyathina, J. Thomson, Proc. Phil. Soc. Glasgow, vol. xiii (1881) 

 pi. iv, figs. 16-16 c, & ibid. vol. xiv (1883) pi. vi, fig. 2. 



Zaphrentis intermedia, J. Thomson, ibid. vol. xiii (1881) pi. iv, figs. 17 & 

 17 a, & ibid. vol. xiv (1883) pi. vi, fig. 1. 



All characters as in Z. delanouei, with the following excep- 

 tions : — In transverse sections the neanic stage is of the constricta 

 type, but in the ephebic stage the septa become amplexoid ; in that 

 condition, unless the section happens to pass over the floor of a 

 tabula, the major septa are short and disconnected in the centre of 

 the corallum. This separation of the septa may take place at 

 varying periods, according to the evolutionary stage of the species 

 (see PI. XXXVII, series 6, 7, & 8), and is usually preceded by 

 a relatively broad, parallel-sided fossula of the parallela type 

 (PI. XXXVII, figs. 6 b & 6 c). 



