180 Messrs. W. K. Parker and T. R. Jones on the 



forms, the shell grows on until the newest chambers extend in 

 their curvature far back, even to three-fourths of a circle, as if they 

 would take on a cyclical growth, such as is normal in Orbiculina 

 and Orbitolites. In the broad, complanate, typical varieties, the 

 septal face is necessarily very long and narrow, and is perforated 

 by one or more rows of roundish or hourglass-shaped, thickly 

 margined passages, subtubular and more or less ecto-ento-sole- 

 nian. This condition is attained by the gradual lineation and 

 subdivision of the lobulate and dendritine aperture. These 

 broad forms are from the seaweed-belt of the warmer seas; but 

 in somewhat deeper water they are gradually replaced by smaller 

 and contracted varieties, in which the spiral portion is small and 

 nautiloid, followed by a long series of either compressed or cylin- 

 drical joint-like cells, presenting altogether an elegant crozier- 

 like outline. In these, as in Dendritina, the aperture is single and 

 lobulate. The name Spirolina has been given to these attenu- 

 ated varieties. Other Foraminifers, especially some varieties of 

 Lituolce, presenting similar elongate shells with a spiral com- 

 mencement, have been included under the same name, thus 

 adding to a confusion of nomenclature. 



Peneroplis is characteristically a creature of warm climate, 

 and does not exist in the North Atlantic, German Ocean, English 

 Channel, and other north temperate seas. We fully agree with 

 Prof. Williamson that the few specimens which he mentions and 

 figures in his ' Monograph ' are strangers to the British Fauna. 

 Since writing the above, we have been favoured with the 

 valuable and beautifully elaborate memoir on Peneroplis, Oper- 

 culina, &c., by Dr. Carpenter (Phil. Transact. 1859), and must 

 refer our readers to that as a source of correct and detailed in- 

 formation respecting the forms under notice, the structure and 

 tissue of which are therein described in a masterly manner ; 

 whilst they are most elegantly and copiously illustrated by some 

 of George West's best lithographs. 



Peneroplis planatus is well figured by Ehrenberg, both as to 

 its shell and its sarcode, in the ' Abhandl. Akad. Berlin/ 1838 

 (1839), pi. 2. figs, a-d'j and its Spiroline forms, under the name 

 of " Coscinospira (Spirolina) Hemprichii/' are also well de- 

 lineated on the same plate, figs, a, b. 



31. Nautilus aduucus. Page 115, pi. 23. figs. a-e. " Recent : 

 Red Sea." 



This elegant Foraminifer, now known by the generic name 

 Orbiculina, which was instituted by Lamarck, has been of late 

 years fully described and illustrated by Prof. Williamson (Trans. 

 Microscop. Soc. 1st ser. vol. iii. p. 120) and by Dr. Carpenter 

 (Phil. Trans. 1856, vol. cxlvi. p. 547, pi. 28. figs. 1-22, arid 

 pi. 29. figs. 1-3). To the latter we are indebted not only for a 

 succinct history of this species, and for a clear exposition of its 



