134 FORAMINIFERA OF THE CRAG. 



Occurrence. — Peneroplis planatus, P. arbuscula, P. cylindraceus. The genus 

 Peneroplis has been subdivided in the ' Challenger' Report into seven well-marked 

 groups, having as their types P. planatus, P. pertusus, P. arietinus, P. cylindraceus, 

 P. lituus,P. carinatus, and P. laevigatas. Where the genus abounds, specimens of 

 each of these types are to be met with, together with intermediate forms linking 

 the types. This fact is remarkably illustrated by the forms found in the 

 Coralline Crag. Of the three specimens discovered, one is referrible to each of the 

 types planatus, arbuscula, and cylindraceus. 



The genus Peneroplis is commonly found in the shallow waters of tropical and 

 subtropical seas ; but occasional specimens have been taken from depths as great 

 as 435 fathoms. The occurrence of Peneroplis as a fossil is somewhat rare. 

 P. arbuscula is recorded from the Aquitanian near Bordeaux, and the Miocene of 

 Vienna. P. planatus (by d'Orbigny, ' Ann. Sci. Nat.,' vol. vii, 1826, p. 285, No. 1) 

 from the Mediterranean, New Holland, and the island of Rawack; the so-called 

 Peneroplis [/] prisca (by Reuss, ' Denkschr. k. Ak. Wiss. Wien,' vol. xxiii, 1864, 

 p. 9) from the Nummulitic Formation of Styria; and P. cylindraceus from the 

 Miocene of Vienna. The Crag specimens were derived as follows : — P. planatus 

 from zone d, Broom Hill ; P. arbuscula from Sudbourne or Gedgrave ; and 

 P. cylindraceus from Sudbourne. 



Genus 3. — Orbiculina, Lamarck, 1816. 

 Brady, Report ' Challenger,' pp. 62 and 208. 

 Part I, 1866, p. 20. 



General Characters. — Chambers subdivided by transverse secondary septa; 

 early segments embracing. Planospiral throughout, or partly cyclical ; contour 

 nautiloid, crosier-shaped, orbicular, or complanate. 



1. Oi;i:in;uNA adunca (FicMel and Moll). Plate III, figs. 43 and 44; Plate VII, 



fig. 4. 

 Part I, 1866, pp. 20 (0. adunca) and 21 (0. compressa) ; and 



Appendix II, Table, Nos. 19, 20. 



Characters. — Fig. 43 is an adult individual in which the initial spiral portion of 

 i lie shell is quite obscured, having been completely and symmetrically surrounded 



