﻿SACCAMMINA. — LITUOLA. 



Gl 



The observations on this species have been made almost solely from Northumbrian 

 specimens, but the same conditions appear to prevail very generally, though varying in 

 •degree. 



Saccammina Carteri is not likely to be confused with any other fossil which we are at 

 .present acquainted with, but unorganized concretional limestones may very readily be 

 mistaken for it, and indeed very frequently are so. I possess a considerable collection of 

 oolitic and pisolitic rocks of Carboniferous, Devonian, and Silurian age, which have been 

 sent to me from various parts of the world under the impression that the constituent 

 spheroids, single or coalescing, were segments of this fossil or of some allied species. In 

 many of these the general resemblance to Saccammina is very striking, and it has often 

 been impossible to come to any conclusion as to the real structure of the rock without 

 having recourse to thin microscopical sections. 



Distribution} — In England the occurrence of Saccammina Carteri is confined to the 

 northern portion of the Carboniferous area. Throughout Northumberland and as far 

 south as Alston in Cumberland, its appearance is limited to the Four-fathom Limestone, 

 but in Weardale (Durham) it has been found in one locality at a considerably higher 

 horizon — the Great Limestone. In Westmoreland only one locality has been noted, and 

 this is regarded as belonging to the lower series of beds — the Scar limestone. 



In Scotland its geological range is very great. It has been traced by the Survey 

 collectors from the Calciferous Sandstone Series, through the Lower Carboniferous Lime- 

 stone group, into the Upper Carboniferous Limestones, though in the later beds it has 

 only been recorded from one or two localities. 



From Belgium I have a number of quite characteristic specimens from the Calcaire 

 •de Vise, the uppermost division of the Carboniferous limestones of that country. 



Genus, Lituola, Lamarck. 



Serpula (in part), Schr'uter. 



Lituola, Lamarck, Blainville, cT Orbigny, Reuss, Parker and Jones, Carpenter, Seguenza, Brady, 



G. M. Dawson, Robertson, Vanden Broeek. 

 Lituolites, Lamarck, Parkinson, Blainville. 

 Si'ikolina (in part), oVOrbiyny. 



Nonioxina (in part), d'Orbiyny, Schidtze, Williamson, Parfitt. 



General characters. — Test free, nautiloid or crozier-shaped, either entirely spiral, or 

 ■spiral in the arrangement of the early segments and rectilinear in the later ones. 



1 For details concerning the distribution of the various species of Foraminifera see the Tables at the 

 end of the paper (pp. 153 — 161). This and the corresponding paragraphs appended to the descriptions of 

 the species are summaries only. 



