FOSSIL INFUSORIA. 159 



Mendion circula/re, which Professor Quekett in the Historical Catalogue 

 describes as " consisting of a series of wedge-shaped bivalve siliceous 

 loricsB arranged in spiral coils ; when perfect, and in certain positions, 

 they resemble circles ; each lorica is articulated by two lateral sur- 

 faces. It is asserted that they can creep about when free from the 

 stalk-plate. (Plate II. No. 16.) 



Cocconimo Boeckii is composed of two lanceolate flinty cases, that 

 taper towards their ends, one of which is attached to a little foot. 

 Each lorica has a line marked in its centre, and transverse rows of 

 dots on both sides ; Ehrenberg says there are twenty-six rows in the 

 one-hundredth of a line. (Plate II. No. 14.) 



Achnanthes Longpipes have at the margins two coarse convex pieces 

 roughly dotted, and two inner pieces firmly grooved ; the inside seems 

 filled with green matter. At one corner they are affixed to a jointed 

 pedicle, which in many specimens contains green granules. They pro- 

 pagate by self-division. 



In a specimen of a fossil Eunotia, found in some Bermuda earth, 

 the flinty case is in four parts ; it is of a half-lanceolate shape, and 

 a little indented on both margins ; two of them have curved rows of 

 dots, and the other two are partly grooved with finer rows. Ehren- 

 berg says they have four openings, all on one side (Plate II. No. 13), 

 presenting a row of dots varying very much in number ; minute striae 

 in some cases extend from each dot towards the middle of the lorica ; 

 and on the circumference there are two of these dots. The spirals 

 and the individual lorica are very fragile, and therefore easily separated 

 from each other. Of a glistening whiteness is the ribbon-like flinty 

 case of FragiUaria pectinalis, which consists of a number of bivalve 

 parts : on the articulating surface there are small grooves, represented 

 in Plate II. No. 15. A singular class of objects are Diatomce floccic- 

 losce, being rather oblong-looking, and joined to each other at oppo- 

 site corners ; sometimes they are grooved on each side. (Plate II. 

 No. 17.) 



A recent specimen of the flinty, wedge-shaped Gomphonenia gemi- 

 natum (No. 11), fixed on a horny stalk, is in the Museum of the Col- 

 lege of Surgeons. Ehrenberg states they have two openings at their 

 hemispherical or indented broad ends. The surfaces are grooved cross- 

 ways. There is another kind, commonly called the Swollen Eunotia, 

 which is generally about from the eleventh to the two-hundreth of 

 an inch in length. A groove, that is widest in the centre, and tapers 

 ofi" to the ends, passes along its centre on both sides, with curved lines 

 proceeding from it. So wonderfully close are these lines or ribs, that as 



