308 University of California Publications in Zoology. [Vol. 4 



Zoarium incriisting-. Zocecia with a siiborbicular, or semi- 

 circular orifice; peristome elevated in front into a more or less 

 prominent mncro. 



« 



77. Mucronella pavonella (Alder) Hincks. 



PI. 23, fig. 78, 79. 



Eschara pavonella Aider, 1864, vol. 4, p. VI. 

 Eschara cribraria Busk, 1856, vol. 4, p. 311, pi. 12, figs. 1-3. 

 Discopora pavonella, Smitt, 1867, pp. 28 and 178, pi. 27, fig. 181. 

 Mucronella pavonella, Hincks, 1880, p. 376, pi. 39, figs. 8-10. 



Zoarium incrusting. partly free forming two layered nndiil- 

 ating", foliaceons expansions. Zomcia large, broadly ovate, alter- 

 nate, strongly areolated round the margin (pi. 23, fig. 78) ; mar- 

 gin much thickened, sending thickened ribs between the areola- 

 tions toward the middle of the front w^all ; middle portion of front 

 wall thin and slightly roughened ; rising into a distinct mucro on 

 the lower margin of the orifice. Orifice large, orbicular, without 

 peristome or nuicro in younger stage (fig. 79), acquiring a thin, 

 low peristome on the upper margin in adult stage (fig. 78). On 

 each side of the orifice an avicularium with rounded mandible di- 

 rected upward. Ooeciaf 



This species is very striking in appearance and may be easily 

 recognized with the naked eye. It has been obtained in small 

 quantity from San Juan Co., Puget Sound. It is reported by 

 Hincks from Queen Charlotte Islands. 



78. Mucronella californica sp. nov. 



PI. 23, fig. 80. 



Zoarium incrusting, forming large, circular colonies of several 

 layers. Zocecia large, ovate, often elongate, in regular lines, al- 

 ternate, except where layers form one above another when they 

 become irregular in growth. Primary orifice circular, secondary 

 orifice formed by the growth of a thin peristome rising in front on 

 the lower margin of the orifice into a rather broad mucro or tooth ; 

 lateral denticles present (pi. 23. fig. 80). A i-ow of pores just 

 inside the margin of each zo(ecium and other pores scattered ir- 

 regularly over the front wall which becomes highly calcified with 



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