100 CARBONIFEROUS AND PERMIAN FORAMINIFERA. 



ENDOTHYRA ORNATA, var. TENUIS, nov. PI. VI, figs. 7, 8. 



Characters. Test free, nautiloid, irregular ; oval or rounded, compressed, very thin ; 

 composed of several convolutions, of which the last only is visible externally. Septation 

 obscure. Surface rough, broken up by very irregular and ill-defined costa3. Periphery 

 sharp, uneven. Diameter, -^ inch (O'SS mm.). 



There can be little doubt that the thin emaciated specimens found in some few localities, 

 and generally in company with Endotliyra ornata, represent merely a starved variety of 

 that species, though they appear very distinct at first sight. The test is outspread and 

 extremely thin, often only like a crumpled scale, and has no traceable septation ; the 

 margin, sharp, without any distinct carina, and usually very irregular. The spiral struc- 

 ture is assumed from analogy, rather than indicated by external marks. It is difficult to 

 give an idea of the tenuity of the shell by a drawing, owing to the irregularity of the 

 surface ; and fig. 7 b is by no means successful. Under the microscope the edge-view 

 often appears as a mere narrow jagged line. 



Distribution. The occurrence of Endotliyra tennis does not exactly correspond with 

 that of its type E. ornata. It is rare alike in the Lower and Upper Limestone rocks of 

 England ; it has been found, though seldom, in the Calciferous Sandstone Series of Scotland, 

 and in the Upper Carboniferous Limestone Group, but is wanting in Lower; in Ireland 

 it occurs in the Castle Espie shale. 



ENDOTHYRA OBLIQUA, Brady. PL VI, figs. 5, 6. 



INVOLUTINA OBLIQUA, Brady, 1869. Eeport Brit. Assoc., Exeter Meeting, pp. 379, 382- 



Characters. Test free, oblong or rounded, compressed ; formed of several convolutions 

 of a band of long arcuate segments, the axis being the long diameter of the test, and the 

 convolutions presenting a long oval transverse section. Surface rough ; with irregular 

 ill-defined costse, more or less parallel to the axis, indicating the position of the septa. 

 Aperture curved, situated near the middle of the inner edge of the long terminal segment. 

 Diameter, - inch (I'O mm.). 



Whether the assemblage of forms grouped under the name Endotliyra ottiqua owe 

 their anomalous characters to external physical agencies or to inherited peculiarity is 

 possibly still open to doubt. Their close relationship to Endotliyra ornata does not 

 admit of question ; but, after the careful examination of a large number of specimens 

 from various sources, I am unable to see how the characters in which they differ from 



