2/0 



2. DlJJARDINIA. 



Having the same external appearance and form as the prece- 

 ding genus ; that is, formed of cells aggregated together in a spiral 

 form, the last cell being furnished with an apical opening ; but the 

 cells appear to have a simple cavity, and are formed of a thicker, 

 harder, uniform shelly coat, which is very closely and uniformly 

 pierced all over with very numerous, minute, equal-sized parallel 



pores. The cavity of the cell 1 in the imperfect specimen which 



I have been able to examine, is simple ; but then it has evidently 

 been well-washed, probably with acid. 



DlJJARDINIA MedITERRANEA. 



Hab. Mediterranean ; Marseilles, on Cardita variegata (J. Rit- 

 chie, Esq. 1817). 



These genera appear to me to form a distinct group of Rhizopoda, 

 which may be called Fenestrifera, which is characterized by the 

 animal being always attached to marine bodies, and the cellular body 

 of the animal being strengthened with spicula and enclosed in a cal- 

 careous cell furnished with a single contracted aperture and pierced 

 with numerous foramens or tubes. 



These shelly bodies differ from all the shells of Rhizopods hitherto 

 known, in being attached, and in the form, structure, and disposi- 

 tion of the cells, which (should the existence of spicula on the body 

 prove a peculiarity of the genus Carpenteria, where alone it has 

 been observed) is sufficient to form a group distinct from the other 

 Rhizopods. 



The existence of these spicula shows that the genus Carpenteria, 

 and probably all the group, forms the passage between the Porifera 

 and Rhizojwds, which has been long suspected to exist, but has not 

 before been described. 



On the Mediterranean specimens of Cardita variegata there is 

 intermixed with the Dujardinia a species of Lepralia, the anoma- 

 lous Polytrema miniaceum, which is formed of numerous layers, 

 one deposited on the other, each formed of a calcareous network, 

 with small equal hexangular interspaces, undefined patches of a 

 crust formed of rough calcareous cells placed side by side like the 

 cells of a Lepralia, but much more unequal in size and irregular in 

 form than the cells usually found in that genus. The parietes of 

 these cells are pierced with numerous equal-sized minute pores like 

 the foramens of Foraminifera, the whole substance of the cell being 

 apparently formed of numerous short shelly tubes placed parallel 

 side by side. The cells are furnished with a small roundish hole at 

 one of their extremities, which is often hid by the convexity of the 

 other cell. 



This may be a peculiar genus of Lepraliadce allied by my genus 

 Cribrillina (Cat. Brit. Radiata, pp. 116, 147), which has " forami- 

 niferous cells," as Professor Busk calls them ; or it may prove to be 

 another form of Foraminifera. If the former, the form of the cells 



