THE ANNALS 



AND 



MAGAZLNE OF NATURAL HISTORY. 



[FOURTH SERIES.] 

 No. 111. MARCH 1877. 



XV. — Description 0/ Bdelloiclina aggregata, a new Genus and 

 Species of Arenaceous Foraminifera^ in which their so-called 

 '■'' Imperforation ' ' is questioned. B j H. J. CARTER, F.R. S. &c. 



[Plate XIII. figs. 1-8.] 



Bdelloidina aggregata^ n. gen. et sp. (PI. XIII. figs. 1-8.) 



Arenaceous, sessile, flat, composed of linear chambers 

 successively applied to each other longitudinally on the same 

 plane, more or less curved simply or tortuously ; following 

 the irregularities of the surface on which the species may be 

 growing (PI. XIII. fig. 1). Composition calcareous. Colour 

 grey. Surface uniformly consisting of rounded grains of 

 calcareous sand of various sizes below 5-1800ths inch in 

 diameter, together with fragments of siliceous sponge-spicules 

 set pearl-like in a minutely granular calcareous material, 

 which thus serves as a cement to the larger portions (fig. 3) . 

 Furrowed by lines or grooves that indicate the form and ex- 

 tent of the chambers respectively (fig. 1, 5), which vary 

 much both in size and shape; tending irregularly though 

 generally to a spiral, planiform aggregation. Presenting on 

 the convexity or outer side of the last-formed chamber a 

 series of circular foramina about 5-1800ths inch in diameter 

 and 10-1800ths inch apart, arranged more or less regularly in 

 a line from one end to the other (fig. 1, a, and fig. 5, a). 

 Chamber constructed on all sides of calcareous sand, &c., 

 similar to that of the surface (fig. 6) ; more or less interrupted 



Ann. & Mag. N. Hist. Ser. 4. Vol. xix. 14 



