124 ZOOPHYTOLOGY. 



unarmed, as in F. truncata, from which F. Barlei, is however 

 distinguished, not only by the far smaller dimension of the 

 cells, but also by the oblique position of the avicularia, and 

 the widely different habit of its growth. F. papyracea, 

 besides its having a small marginal spine on each upper 

 angle, has no avicularia, so far as I am aware, and also differs 

 from F. Barlei very widely in habit. 



This is an important addition to the British Zoophy- 

 tological Fauna ; and it is curious that so large and well- 

 marked a species should have hitherto escaped recognition. 



Pam. 2. Membraniporida?. 

 Gen. 2. Membra nipora. Blainv. 

 1. M. cornigera, n. sp. PI. XXV, fig, 2. 

 M. incrustans ; cellulis pyri/ormibus, superne angustatis, margbie glabro 

 splnis 6 armato quarum infimis bifurcatis ; lamina subgranulosd. Aviculariis 

 crebris, inter cellulas sparsis, mandibulo semicirculari ins t metis. 



Incrusting; cells pyriform, contracted above, expanded below, with a 

 smooth margin armed witli three pairs of spines, of which the lowest arc. 

 forked ; lamina subgranular. Avicularia numerous, interspersed among the 

 cells, with a rounded or semicircular mandible. 



Bab. Shetland, Barlee. 



When in a state of tolerable preservation, no confusion 

 can be made between this species and any other. Its nearest 

 ally, perhaps, is M. Flemingii, in which the form of the cell 

 is pretty nearly the same, and the number of marginal spines 

 equal ; but the disposition of the aivcularia differs, so that 

 even in much worn specimens, sufficiently distinct characters 

 may in most cases be perceived. When the marginal spines 

 are uninjured, the peculiar forked form of the lowest pair 

 will at once suffice to distinguish the present from any 

 other British species. In M. Flemingii also, the mandible of 

 the avicularium is acutely pointed, whilst in M. cornigera it 

 is rounded and obtuse. 



M. vulnerala, n. sp. PL XXV, fig. 3. 

 M. incrustans ; cellulis subpyriformibus seu oval/bus, superne angustatis ; 

 aperturd parvd, semicircularid ; lamina granulosa, ulrinque Jissurd sigmoided 

 plerumque ornatd ; margine granulosa, inermi ; vibraculis intercellulas sparsis. 



Incrusting ; cells subpyriform or suboval ; aperture small, semicircular 

 lamina granular, usually with a narrow sigmoid slit on either side ; margin 

 granular, unarmed. Vibracula scattered among the cells. 



Hab. Shetland, Barlee ; on stone. 



This, so far as I am aware, is the only Membra nipor -a 

 furnished with vibracular instead of avicularian organs. 



