SM1TTIA LANDSBOROVII. 



343 



Form ft (?porifera, Smitt). Zocecia short-ovate or 

 rhombic, flatfish, very thickly punctured over the 

 entire surface ; orifice (secondary) suborbicular, with 

 two minute lateral denticles ; central tooth wanting ; 

 peristome very slightly elevated; suboral avicularium 

 subcircular or oval. Ooecia rounded, not hooded, 

 obscurely punctured ; spatulate avicularia none (?). 

 (Plate. XXXVI. fig. 1.) 



Fi K . 15. 



Smitt ia Land&borovn. 



RANGE OF VARIATION. The cell in the typical form 

 is usually elongate, often somewhat rectangular, with a 

 flat t ish surface and thin walls ; but it is also not unfre- 

 quently, within the limits of one and the same colony, 

 short and ovate, or rhomboid. The peristome is more or 

 less developed : sometimes it forms an elevated wall 

 round the mouth, which is cleft in front into a very 

 deep fissure or sinus ; in other cases it is very slightly 

 raised. These differences affect the form of the secondary 

 orifice. 



The primary aperture is to some extent subquadrangular 

 (" rotundato-quadranffularis ") ; the secondary orifice, 



