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



The immersed oa?eiiim with the pore which seems sometimes to 

 assume the shape of a small operculum, resembles that of Cellaria. 

 This species is extremely interesting and deserves closer study. 

 It is reported as luxuriant in growth at Houston-Channel, Queen 

 Charlotte Islands. It occurs in small quantity in our collection 

 from Puget Sound, Washington, and from Mendocino City and 

 Pacific Grove, California, where it occurs between tide marks. 



Porella Gray. ^ 



Cellepora, (part) Fleming, 1828. 

 Porella Gray, 1848. 

 Lepralia, Busk, 1854. 

 Porella, Hineks, 1880. 

 Porella, Hiucks, 1884. 



Zoarium incrusting or erect, foliaceous with a single layer of 

 zooecia, or ramose. Zooecia with the primary orifice semicircular ; 

 secondary orifice elongate, inversely subtriangular, or horseshoe- 

 shaped, inclosing an avicularium, usually with a rounded mand- 

 ible. 



This genus is apparently not well represented in this fauna. 

 But one species appears and that is incrusting. 



69. Porella concinna (Busk) Hineks. 



PI. 22, fig. 65. 



Lepralia concinna Busk, 1854, pt. 2, p. 67, pi. 99. 

 Porella concinna, Hineks, 1880, p. 323, pi. 46. 

 Porella concinna, Hineks, 1884, vol. 13, p. 50. 



Zoarium forming an opaque, white, closely adherent incrusta- 

 tion on stones, shells, etc. Zooecia (pi. 22, fig. 65) ovate, slightly 

 convex, punctate; orifice orbicular, deeply sunk in older zooecia, 

 with an oval avicularium within or upon its lower margin ; im- 

 mediately below the avicularium, and often hiding it, the zooecial 

 wall frequently rising into a rounded prominence or mamilla, 

 mam.; on each side of the orifice rostra are often formed by a 

 thickening of the wall; frequently a small avicularium, or pore 

 at one side of the mamilla. Oacia small, sparsely punctate, often 

 having an umbo on its front surface 



