542 Transactions of the Society. 



glossy surface. The test, whilst finely arenaceous, exhibits great 

 uniformity of structure, and when viewed in section by transmitted 

 light exhibits a peculiar white opacity of texture not commonly 

 Been in members of this genus. 



Distribution. — It is a form apparently much limited in dis- 

 tribution. Recorded in four samples, three of these belonging to the 

 "D" limestone of the Cowburn and Tipalt districts, and the other 

 in " K " limestone, near West Stone Folds, Cowburn. In the " D " 

 limestone it is common. 



Endothyra radiata, var. Tateana, nov. Plate IX. figs. 13-15. 



Test free, nautiloid, nearly circular in peripheral outline, com- 

 pressed laterally, embracing, umbiHcus sunken, slightly inequi- 

 lateral, peripheral margin thin or subcariuate ; convolutions numerous, 

 five to six in fully grown examples ; chambers very narrow and 

 numerous, from 25 to 40 in last convolution ; septal walls double ; 

 sutural lines slightly excavated ; septation sometimes indistinct and 

 often showing considerable irregularity in arrangement on exterior 

 surface. Texture finely arenaceous with large proportion of calcareous 

 cement. Diameter of fully grown specimen 1/25 in. 



A fine variety of Eudothjra, difiering in some minor particulars 

 from E. radiata. The shell attains about twice the diameter of 

 typical specimens of the latter species ; it is more symmetrical and 

 compressed, and the segments are more numerous and less regular, 

 often showing crenulations, meeting at various angles on the surface 

 of the test. The duplication of the septal walls is also an important 

 feature, and one that has not been observed in connection with any 

 other members of the genus. It is well seen, not only in transparent 

 sections of this form (Plate IX. fig. 15), but in those examples 

 which have been subjected to a degree of weathering, as shown in 

 fig. 14 of the same plate. The double septation gives a higher 

 character to the genus than was at first indicated, and is another 

 feature confirmatory of Mr. Brady's opinion, expressed when working 

 out this interesting pakeozoic type, of the close analogy which the 

 genus bears to the more recent and distinctly calcareous Kotaliue series, 

 with which Endothyra in its various modifications is closely isomor- 

 phic. 



I have great pleasure in associating this variety with the name 

 of the late Mr. George Tate, F.G.S., of Alnwick, who was one of the 

 earhest and most enthusiastic students of the palaeontology of North- 

 umberland. 



Distribution. — Endothyra radiata, var. Tateana is not uncommon 

 in the lower Carboniferous beds of south-west Northumberland. It 

 was noted in the upper beds of the Great Limestone at Blagill, Alston ; 

 but all of the twenty-four localities in which it has been observed, 

 with the exception just noted, are at horizons included between the 

 " B " and " N " limestones of the Cowburn and Tipalt valleys. 



