8 Mr. W. C. Williamson on the Recent 



lour, becoming of a paler hue as we approach the larger cells ; 

 the terminal ones being almost colourless. In Rotalina Beccarii 

 this difference is scarcely to be observed, all the cells being nearly 

 transparent ; and in Polystomella crispa, the animal portions fill- 

 ing the innermost and outermost cells appear to exhibit no dif- 

 ferences of transparency or colour. A slight deepening of the 

 colour is observable in the young cells of Quinqueloculina semi'- 

 nulum. 



It is from Rosalina globularis that the best specimens of the 

 decalcified animal membrane are to be obtained, and from Rota- 

 lina Beccarii the next; these two, especially the former, pre- 

 serving their contour the best, owing to the greater density of 

 the lining membrane. In Polystomella crispa, and in the Quin- 

 queloculime, this membrane is so exceedingly thin, and the con- 

 tained animal matter in such a thoroughly fluid state, that less of 

 a definite form is left on drying the decalcified animal than would 

 result from submitting Paramecium aurelia, or many others of the 

 Polygastric Infusoria, to a similar process, corroborating M. Du- 

 jardin^s observations, though not the inferences which he deduced 

 from them. 



On treating various species of Lagena with dilute nitric acid, 

 in the same way that I had done the other Foraminifera, the re- 

 sults were of a precisely opposite character to those I had pre- 

 viously arrived at, but analogous to those obtained by Milne 

 Edwards in operating upon Eschara. I found a strong animal 

 membrane, which, had the organism not been dried, would evi- 

 dently have been flexible ; not lining the cavity of the cell, but 

 retaining all its external form. This was obtained most easily 

 from L. Icsvis, var. Amphora (fig. 3), and L. striata (fig. 5), in old 

 specimens of which the decalcified membrane was of considerable 

 thickness. In L. striata the membrane was very thin and trans- 

 parent along the costse, but in old specimens thick and opake in 

 the intervening spaces, the latter portions being easily separated 

 in the form of long shreds. The same transparency in the mem- 

 brane was observable in the translucent reticulations separating 

 the areolae of Entosolenia squamosa, the areolae being opake. 



The only species which I have hitherto had the opportunity of 

 examining in a fresh state is the Lagena [Entosolenia) marginata, 

 which was rather abundant amongst the branches of an Anten- 

 nularia, which Mr. Jeffreys sent to me from Falmouth, whilst still 

 moistened with sea-water. In these specimens, no trace of organi- 

 sation was observable in the soft animal ; each cell being filled 

 with a perfectly transparent gelatinous fluid, like that contained 

 in the outermost cell of a Rotalinaj but even still more completely 

 colourless. 



The existence of foramina in many of the species, implying 



