258 University of California Publications in Zoology. [Vol.6 



is the presence on the surface of the colony of pores of different 

 sizes (pi. 24, fig. 53). These pores are either zooecial apertures 

 i zoe. nj'.' or the apertures of other smaller tubes, the so-called 

 interstitial canals {inter, can.) occurring between the zooecia. 

 Busk describes the surface of a colony or branch as < vt n. meaning 

 doubtless, that it is not roughened by projecting tubes. This 

 is the usual appearance except in portions where the surface 

 may be protected from contact with other objects. In sueh 

 protected places the zocecial tubes extend a considerable distance 

 beyond the general surface (fig. 55, zoe.) the zooecial projection 

 being non-porous, frequently annulated, expanding sometimes 

 as it rises. This extension of the zoceeia beyond the surface is 

 mentioned also by Whiteaves ( '82) as characteristic of the 

 Vancouver form. The smaller pores are apertures of relatively 

 minute tubes whose function, as Busk suggests, may be to afford 

 means by which fluid may permeate the colony. The walls of 

 both zooecia and interstitial canals are porous, as are the zoceeia 

 throughout the Cyelostomata. 



If one examines the growing tips of a branch, the tubular 

 openings found there are for the most part those of the zooecia in 

 various stages of maturity. Between them, formed by minute 

 triangular spaces where the walls of zoceeia do not come into 

 contact, are the interstitial spaces. These, which at first are 

 triangular or quadrangular, soon become circular. As growth 

 proceeds, both zoceeia and interstitial canals curve outwards, and 

 although at the growing tips these tubes are parallel to the axis 

 of the bianeh, when adult they curve almost at right angles with 

 the axis of a branch and the apertures open laterally, the larger 

 zocecial apertures being surrounded with a circlet of small 

 interstitial openings (fig. 53). 



101. Heteropora pelliculata Waters. 



PI. 25, figs. 51, 52, 53, 54, 55. 



Heteropora pelliculata Waters, 1879, vol. 2. pi, 15, figs. 1, 2, 



3, 4. and 7. 

 Heteropora neozealanica Busk, 1S79, vol. 14, p. 725. pi. 15, figs. 1-4. 

 Heteropora sp. ? Whiteaves, 1882, ser. 3, vol. 24. p. 27!». 

 EntalopJiora capitata Robertson, 1900, vol. 2, 328. pi. XXI, figs. 11 



and 13, not fig. 12. 



