294 PROCEEDINGS OF THE NATIONAL MUSEUM voi>. los 



Affinities: Smittina excertaviculata is like the fossil Australian 

 species Porella punctata MacGillivray (1895, p. 91, pi. 12, figs. 8, 10, 

 11) in the shape and general appearance of the secondary orifice but 

 differs from it in having a much more densely punctured frontal. In 

 this respect, S. excertaviculata resembles another fossil, Smittia crib- 

 raria MacGillivray 1885 (1895, p. 93, pi. 12, figs. 16-17), but differs 

 from this earlier species in the shape of the secondary orifice. Ovicells 

 were unavailable for description in both fossil species. Smittina 

 excertaviculata thus seems to be more closely related to the Australian 

 fossil forms than to more recent species. 



Smittina obicullata, new species 



Plate 27 



Diagnosis: Colony unilaminate to bilaminate, encrusting or erect, 

 forming broad blades. Zooecial frontal gently convex or flattened 

 except for the frontally projecting peristome and elevated suboral 

 avicularium. Frontal sometimes granular, perforated by numerous 

 pores. Mural rims thin and salient. Secondary orifice outlined by 

 a partial peristome, raised highest in front and less at sides. Peri- 

 stome broadly notched medially. Primary orifice broadly curved, 

 wider distally. Two cardelles and a low, broad, truncated lyrula. 

 A small, rounded to elliptical avicularium below peristomial notch 

 in some zoids. Mandible nearly hemispherical, with a pair of con- 

 verging sclerites. Ovicell thin-waUed, smooth, globose, punctured 

 by several pores and encroached upon by the peristome and neigh- 

 boring zoids at the sides. 



The name of this species derives from the Latin "obicis" (barrier, 

 bar, wall) and "ulus" (diminutive) because of the peristome, which 

 forms a small barrier or wall in front of the primary orifice. 



Measurements: Minimum to maximum and average measure- 

 ments, in millimeters, are given below (for explanation see p. 271). 



Z-L, 0.864-1.101 (1.001) Pr-Or-W, 0.173-0.230 (0.202) 



Z-W, 0.418-0.518 (0.446) Se-Or-L, 0.158-0.230 mm. (0.193 mm.) 



Ov-L, 0.274-0.317 (0.295) Se-Or-W, 0.202-0.259 (0.237) 



Ov-W, 0.288-0.360 (0.347) PN-L, 0.050-0.122 (0.084) 



Av-L, 0.144-0.173 (0.159) PN-W, 0.043-0.086 (0.066) 



Av-W, 0.115-0.144 (0.134) Ly-L, 0.022-0.029 (0.027) 



M-L, 0.072-0.101 (0.094) Ly-W, 0.058-0.086 (0.073) 



M-W, 0.079-0.122 (0.104) Op-L, 0.209-0.223 (0.216) 



Pr-Oi-L, 0.144-0.173 (0.152) Op-W, 0.122-0.144 (0.131) 



Zoarium: Zoaria a dull ivory or grayed buff color and up to 3.5 

 by 4 cm. in size. They form broad-bladed bilaminate chips after 

 arising from the unilaminate encrusting (substratum) layer. The 



