Dr. J. E. Gray on Carpenteria and Dujardinia. 385 



C. BALANIFORMIS. 



Hah. Philippine Islands, on Porites, Card'ita, Pecten, and other 

 shells. 



The conical shell is furnished with a single contracted aperture 

 at the apex of the cone ; as each cell is formed it closes the aperture 

 of the preceding cell, so that only one is seen at the top of the cone. 

 Some specimens show two or rarely three apertures at the tip of the 

 cone ; but this arises from the tip having been broken ; these aper- 

 tures are of a larger size and irregular form, very unlike the con- 

 tracted uniform-shaped aperture of the last cell. 



When the shell is worn, or partly destroyed by acid, the thin part 

 between the network is destroyed, leaving only the calcareous ribs, 

 which fill the greater part of the cavity, leaving a cavernous calca- 

 reous body somewhat like a sponge turned into stone. 



A section of the parietes of the cells appeared to be formed of 

 polyhedral plates separated from one another by a rather opake line, 

 as if formed by the union of the edges of the plates ; and each plate 

 is pierced with a number of uniform-sized, regularly disposed cir- 

 cular perforations, leaving a nearly uniform imperforated belt round 

 the margin of each plate. 



The specimens on the shells of Cardita variegata from the shores 

 of the Mediterranean are so diiferent in substance and sti-ucture 

 from those found (on the same species of shell among others) on 

 the shores of the Philippines, that I propose to form for them a 

 second genus, named in honour of M. Felix Dujardin, the Professor 

 of Biology and Dean of the Faculty of Sciences at Rennes, who first 

 described the animal of the many-chambered microscopic shells, 

 which had before been generally considered as the residence of 

 Cephalopods ! (the most eom[)licated organized mollusca), instead of 

 the most simply organized animal. 



2. Dujardinia. 



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 a]jical 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 ? in the imperfect specimen which 



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

 been well washed, probably with acid. 



Dujardinia Mediterranea. 



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

 chie, Esq. 181 7). 



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

 which may be called Fenestrifera, characterized by tlie animal l)eing 



