I 



448 Kev. T. Ilincks on the 



ovate, much elevated centrally below the mouth, the wall 

 sloping steeply clown to the margin of the cell ; surface dense, 

 smooth, rather glossy, areolated round the edge, ridges radi- 

 ating towards the centre ; orifice orbicular, with a small central 

 sinus, not contracted at the opening ; peristome not ele- 

 vated ; immediately below the orifice, at one side of the sinus, 

 a rostrum bearing on one side a pointed avicularium) the beak 

 very slightly bent at the extremity, mandible directed up- 

 wards, the rostrum rising into a short mucronate point behind 

 the avicularium ; very commonly on the front of the cell, near 

 the bottom, a much-raised avicularium (mounted on a promi- 

 nent elevation) with a pointed mandible directed straight out- 

 wards. Owcium rounded, smooth, much broader than high, 

 with a tall oral arch filled in by a calcareous plate. 



Off Cumshewa, in 20 fathoms, forming a brownish spread- 

 ing crust. 



Schizoporella prist ina, n. sp. (PL XVII. fig. 6.) 



Zooecia ovate, irregularly disposed and shaped, moderately 

 convex, separated by raised lines ; surface thickly punctured, 

 presenting (in older states) a reticulated appearance ; orifice 

 rounded above, the lower margin curving out below the oper- 

 cular denticles into a wide rounded sinus, so that the mouth 

 appears almost circular, peristome not raised, sometimes a 

 thickened granulous border surrounding the orifice in front. 

 A ricularia none. Ocecium (?) . 



Dolomite Narrows, on shell. 



The oral sinus in this species takes its origin immediately 

 below the denticles on which the opercular valve works, and 

 is somewhat difficult to recognize. At first sight the orifice 

 seems to be circular, as the sinus occupies nearly the whole 

 of the inferior margin. The lower cell in the figure (PI. XVII. 

 fig. 6), which is represented with the operculum in situ, is 

 defective in not showing the contraction below the denticles. 



We have here, we may suppose, one of the primitive forms 

 of the sinuated orifice, from which others may have been de- 

 rived by contraction (more or less) or other modification of 

 the marginal curve. The suboral pore of certain genera pro- 

 bably owes its origin to the isolation of the most specialized 

 form of sinus, a central notcli with contracted aperture. 



Schizoporella maculosa, n. sp. 



Zooecia quincuncial, rather small, moderately convex, su- 

 tures shallow ; surface shining, covered with small punctures, 

 which are closed in by a brownish membrane, and give a 





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