MEMBRANIPORID^E. 47 



parative size, in accordance with which the walls of the cells are very thick and strong. 

 The peculiar production of the anterior part of the peristouie into a sort of pointed spout,, 

 and the existence of an aviculariuni on each side in front of the ovicell, are amongst the 

 other most striking peculiarities. It should be remarked that the avicularia are formed 

 only on the fertile cells, no vestige of such organs being discernible in the cells not 

 furnished with an ovicell. 



14. L. BICORNIS (. sp.) PI. VIII, figs. 6, 7. 



- 



Cellulis ovatis, sen doliiformibus, umbonatis, superficie minute granulosa, margined 

 circa serie punctorum unica ornatis. Orificio orbiculari, processu cylindrico ascendente, 

 aviculariuni apice gerente, utrinque munito. Ovicellulis globosis. 



Cells ovate or barrel-shaped, surface finely granular with a single row of punctures 

 around the margin ; orifice orbicular ; an ascending cylindrical process on each side of the 

 orifice, having an aviculariuni on the apex ; an elongated ascending conical umbo in front 

 of the orifice ; ovicells globose. 



Habitat. C. Crag, on shell, S. W. 



15. ? L. BIAPERTA, Michelin (sp.} PI. VII, fig. 5. 



Cellulis quincuncialibus, seu serialibus, ovoideis, convexis, confluentibus, vibracularium 

 elevatum uno latere in partera superiorem gerentibus. Orificio orbiculari, infra sinuato, 

 peristomate simplici. 



Cells quincuncial or serial, ovoid, convex, confused ; surface smooth ; orifice orbicular, 

 with a sinus below ; peristonie simple ; a projecting vibracular process on one side at the 

 top of the cell. 



ESCHAKA BIAPERTA, Michelin, Icon. Zooph., p. 330, pi. Ixxix, fig. 3. 



Bearing some resemblance to L. Hyndmanni, Johnst., the species to which M. 

 Michelin probably refers, L. biaperta is distinguished from it 1st, by the peristorne 

 never being thickened or raised, as it usually is in L. Hyndmanni ; 3d, by the absence of 

 pores at the border of the cell ; and 3d, in the far higher position on the cell of the raised 

 and perforated process, which doubtless represents the support of a vibracwlum similar to 

 that of L. Hyndmanni. The species, however, must be regarded as suspiciously near to 

 L. Hyndmanni, which, it should be remarked, enjoys a tolerably extensive range in the 

 present state of the globe, being found as far south, at any rate, as Madeira. M. 

 Michelin's figure of the cell corresponds so closely with nature, that little doubt can be 



