British species of the genus Lagena. 9 



the presence of pseudopodia, renders it probable that the animal 

 of all the LagencE will eventually be found to be like that of other 

 Foraminifera, viz. a gelatinous substance capable of projecting 

 minute filaments, used probably as organs of progression, and 

 also of receiving foreign bodies into its interior by means of the 

 tubular orifice, by which substances it is nourished. Whether in 

 any species the orifice at the extremity of the tube be furnished 

 with a ciliobrachiate polype like that of the Eschara or not, is 

 doubtful. The pecuHarity in the structure of the membranous 

 part of the cell, resembling that of Eschara and differing from the 

 RotalincE, would indicate the possibility of some resemblance in 

 this point, but my observations on Lagena marginata render it 

 scarcely probable. 



The existence of the internal tube of the Entosolenice, though 

 so different from what generally occurs amongst the Foramini- 

 fera (in which all siphuncular appendages usually project ante- 

 riorly and not retrally, as has been already observed by M. Ehren- 

 berg), constitutes no real difficulty in the way of classing them 

 together ; since in an elegant species of Polymorphina, not un- 

 common in the Boston deposit, and sometimes occurring on our 

 own coast, the outermost cell is furnished with a precisely simi- 

 lar internal prolongation of the terminal oral ? orifice, and which 

 I have not hitherto seen noticed by any observer. 



As regards the mode of growth of the Lagena one thing is 

 certain, viz. that in the young state the cell is very thin, vitreous 

 and ti-ansparent, whilst it becomes more and more opake with 

 age. Here again we have another resemblance to Eschai'a, in 

 which the gemmule after fixing itself to some object first covers 

 itself with a very thin calcareous case, which it gradually thick- 

 ens by the addition of calcareous particles. In L. striata the 

 young cells, which are comparativehj small, are perfectly trans- 

 parent, whilst the large specimens commonly found in the cabi- 

 nets of collectors are strong and quite opake* excepting along the 

 costse. From an examination of an immense number of speci- 

 mens, it soon became evident to me that the animal must have 

 possessed the power of enlarging and thickening its cell with in- 

 creasing age. This fact first led me to suspect that in its struc- 

 ture it would approach nearer to Eschara than to Rosalina ; an 

 induction which subsequent investigation confirmed. Owing to 

 its form, the cell could not have been so enlarged if it had been 

 merely a calcareous secretion from an internal membrane. It is 

 only in young specimens of the true Lagence that the long ex- 

 ternal neck is found perfect. On older specimens it is almost 

 always worn off : this is especially the case with L. striata. 



* \x\ some instances tins opacity arises from the deposition of calcareous 

 matter, in others from a thickening of the membrane. 



