Manchester Memoirs, Vol. Ixii. (19 17) 29 



The only species which has been found and which is here 

 described, is an isomorph of Carpenteria proteiformis Goes. 

 In fact on a cursory examination my examples were thought 

 to belong to that species but a second glance showed that a very 

 different form had been discovered, and one that merited the 

 formation of a new genus to receive it. 



The tests are not all formed on the exact model described 

 above, which is only of general application, but they follow 

 various modifications of it. It has therefore been deemed 

 necessary to give a series of drawings illustrating the different 

 forms observed. 



The more regularly formed tests commence by a spiral 

 series of three or four chambers somewhat resembling 

 Truncatulina lobatula (W. & J.). The last chamber of this series 

 is narrower and about double the height of its predecessor. Its 

 oval aperture is situated at its highest point. It is on the summit 

 of this higher and narrow chamber that the next one is added so 

 that the test now assumes a tower-shaped or columnar form. 



The shell-wall is finely arenaceous, compact, smooth in- 

 ternally and white in colour. 



This new genus is nearly related to Trochammina by its 

 preliminary spiral growth, and to H ormosina by the form of 

 its latter segments, the composition of its shell-wall and the 

 character of its oral apertures. 



In the only gathering (No. 5) where this form was found 

 it was. frequent and the specimens were sometimes filled with 

 calcite and sometimes with pyrites. 



(Halkyard's diagnosis of his specimens appears to have 

 been somewhat perfunctory. A closer examination of the 

 material and especially of the broken and ground down 

 (opaque) sections which he had prepared would have disclosed 

 the fact that the wall of the test was not truly arenaceous, but 

 consisted of an inner calcareous and finely perforated shell 

 incrusted with a thinner layer of very minute mud particles. 



The existence of a similar double, wall has been long known 

 to exist in many Textnlarice and is not considered of even sub- 

 generic importance. 



Except in respect of this outer investing coat and the fine- 

 ness of the perforations of the inner wall the specimens do, not 

 differ appreciably from Carpenteria proteiformis, Goes, and 

 the presence of typical coarsely perforate fragments of this 

 species in the Biarritz strata need not in our opinion prevent 

 the sub-arenaceous specimens, assigned by Halkyard to a new 

 genus, from being regarded as mere variations of Goes' pro- 

 tean type, 



