Burnet: Notes on the Upper Chalk of Lincolnshire. 211 



informs me that they may be either dwarfed adults or immature 

 specimens (the pHcated stag-e not reached). 



R. cuvieri is the commonest species of Rhynchonella, but it is, 

 generally speaking, much below the average size. R. limhata 

 and R. plicatilis, var. octoplicata are quite characteristic of 

 Upper Chalk. 



The common occurrence of Kingenn lima in this part of the 

 chalk is a feature peculiar to Lincolnshire, or perhaps it would 

 be more correct to say, peculiar to the nothern chalk. It was 

 first found in the Upper Chalk of Lincolnshire by Mr. W. Hill, 

 who also discovered it in the Holaster planus chalk at Enthorpe, 

 Yorks. It has also been found by Dr. Rowe in the Terehratulina 

 zone at Reighton, and in the Holaster planus zone near Flam- 

 borough. In the course of my own very limited collecting 

 from the Yorkshire Chalk I have obtained specimens from both 

 these zones in inland Yorkshire, so it would appear to be not 

 uncommon. 



Echinoderms are generally common in the Holaster planus 

 zone, but such is not the case in Lincolnshire. The commonest 

 forms are Holaster planus and H. placenta. Echinocorys is also 

 found, but the specimens are too imperfect or too much crushed 

 to show any characteristics of shape. As in Yorkshire, 

 Micrasters are very rare. The Micraster cortestiidinariuni from 

 Ulceby is the only example of that species which has been 

 found in Lincolnshire It is about the usual size, having a 

 length of 48 mm. and a breadth of 52 mm. The most remark- 

 able of the echinids is Infulaster excentricus. This fossil is 

 common in the zone of M. coranguinum, and also occurs in the 

 higher zones, but its occurrence in the lowest part of the Upper 

 Chalk is quite remarkable. Mr. Rhodes, of the Geological 

 Survey, collected a specimen from the Acthorpe quarry, a mile 

 and a half north-west of Louth. In addition to the example 

 which I found at Limber, I have also obtained a specimen from 

 a quarry near Malton which is either in the Holaster planus 

 zone, or just within the zone of M. cortestudinariuni (probably 

 in the former). 



Dr. Kitchin has carefully examined the two specimens, and 

 has compared them with the one from Acthorpe, and he says : — 



' The specimens are very good examples of Infulaster excen- 

 tricns Rose. I find that this is a variable form as regards 

 outline. The elevation of the apex, the degree of dorsal 

 carination, and the slope exhibited by the margin of the anteal 

 sulcus are characters subject to much variation, but I do not 



1906 July I. 



