4 Mr. W. C. Williamson on the Recent 



nuteness of the species composing it presents a great obstacle to 

 an accurate examination." 



The more recent writers have followed in the steps of those 

 who preceded them, with two exceptions. 



Professor MacGillivray, in his work on the ' Molluscous Ani- 

 mals of Scotland/ &c., made the first attempt to classify the Bri- 

 tish Foraminifera according to the comprehensive system of 

 D'Orbigny, and at the same time reunited the Lagena to those 

 organisms from which D'Orbigny had separated them. 



In ]839 Ehrenberg laid before the Academy of Sciences at 

 Berlin the brilliant results of his investigations into the structure 

 and relations of the Foraminifera. He com})letely exploded the 

 long-received opinion that they were Cephalopoda, and proved 

 beyond doubt that they were zoophytic, being in fact Bryozoa 

 allied to Flustra, Eschara, Cellepura, &c. In his classification of 

 the Bryozoa according to his new views, of which a copy was 

 published in the 'Annals and Magazine of Natural History' 

 for 1841, vol. vii. p. 303, he places some of the Lagence at the 

 head of the list of Foraminifera, under the name Miliola ; ap- 

 parently considering them the most simple and rudimentary form 

 of that curious group. This is I believe the last published notice 

 of the genus, except what is to be found in Thorpe's 'British 

 Marine Conchology' (which contains no more than had been 

 previously given by Dr. Fleming and other conchologists), and a 

 few remarks in the memoir before alluded to on the microscopic 

 character of the Levant mud. 



On subjecting the Lagence from the Boston and March deposits 

 to a close examination, and especially by adopting Ehrenberg's 

 plan of mounting them in Canada balsam and viewing them as 

 transparent objects by means of transmitted light, I soon ob- 

 served some interesting facts which had apparently escaped the 

 notice of our British conchologists. One of the first was, that 

 these objects, the whole of which consist invariably of one iso- 

 lated cell or chamber, require, nevertheless, to be divided into two 

 distinct groups or genera; the one characterized by a long ex- 

 ternal neck or tube, with a small patulous orifice at the free ex- 

 tremity, projecting from the upper part of the cell (see PL I. figs. 

 1, 6, 9 & 10.) ; whilst in the other there exists a very similar tube, 

 only occupying a reversed position. Instead of projecting exter- 

 nal}]/, it descends into the internal cavity ; still taking its rise 

 from the upper portion of the cell, towards the lower part of the 

 interior of which, the patulous orifice of the tube presents itself 

 when it attains its full length (see Plate II. figs. 14, 16 & 22). 



A little time after making this discovery, I received from Dr. 

 Bailey of New York, specimens of Lagena striata (which is one 

 of those having an external tube), and attached to it was the 



