PORAMINIFERA. 215 



from whose beautiful figures our cut has been copied. 

 Mr. Williamson reduces the British species to eight, and 

 disposes them under two groups, Lagena proper, distin- 

 guishedby havingthe oral extremity of the flask produced 

 into an external tubular neck ; and fintosolenia, charac- 

 terised by an internal tube, rising from the upper ex- 

 tremity of the shell, and prolonged downwards into its 

 cavity ; as if the neck, instead of being prolonged from the 

 body, were introverted. Four species of each genus are 

 described. The shells .^ 

 of other Foraminifera 

 are of a more complex 

 structure, consisting ; 

 of a number of dis- 

 tinct chambers, ar- 

 ranged one after an- 

 other, like those of a nt 



Nautilus, communicating with each other by pores, and 

 variously disposed, either in a spiral order or in straight 

 or curved lines. There are many species, placed in 

 several genera, found on the British coasts. Two of the 

 commonest species are represented in our figure. Both 

 may be found in a dead state in the fine shelly drift-sand, 

 and living specimens may often be seen attached to the 

 stems of various small Algse. Such structures as these 

 curiously imitate the chambered shells of the Nautili, 

 and still more strikingly resemble, in miniature, the 

 fossil remains of an earlier world. Their resemblance to 

 the Ammonites, in particular, caused them, at one time, 

 to be referred to a similar class of beings ; and their 

 minute size was regarded as characteristic of a worn-out 



