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



of growth, arangement of zooecia, etc., have had to be taken into 

 consideration, rather than the position or form of the ovieell, or 

 of its aperture, since in these genera either the ovieell or its 

 aperture, or both, are unknown, or known to a limited degree. 



Since the ovieell is so important a feature of the cyclostoma- 

 tous colony it may be well at this time to give a general descrip- 

 tion of it. The fullest and most complete account of it in certain 

 typical cases may be obtained from the work of Harmer already 

 referred to. That investigator ( '91 ) has shown conclusively that 

 in one genus, Crisia, the ooecium is a modified zocecium. At a defi- 

 nite place in an internode a zocecium becomes inflated ( pi. 18, fig. 

 2, o< . \ and acquires a tubular aperture which may remain circular 

 in shape or become more or less compressed. In the genus 

 Tubulipora, the same investigator ('98) has shown that the 

 ocecium is an inflated zocecium which, however, may grow large 

 and cover a considerable portion of the surface of a colony by 

 extending into the spaces between the rows of zooecia ( pi. 21, fig. 

 25, oe.) . In Lichenopora, Harmer ('96) describes the ooecium as 

 a complex structure "whose growth is intimately connected with 

 the development of the external features of the colony." That is. 

 it begins to form when the colony contains but three or four 

 zooecia and increases in size as new zooecia arise, there being 

 but one ocecium to each colony. In matured colonies this ovieell 

 occupies a central position, it being the "free central area" of 

 Ilincks ('80). It is further characterized by some writers, e.g., 

 Busk ('75), and Waters ('90), as possessing cancelli. These 

 cancelli are the reticulations which may be seen in the ovieell of 

 a full grown colony of Lichenopora (pi. 25, fig. 48, oe.). This 

 reticular appearance is due to secondary thickenings or bars 

 supporting or strengthening the roof of the ovieell which forms 

 around the zocecia and over the spaces between them, as well as 

 over the central space of the colony from which the first or oldest 

 zocecia radiate (pi. 25, fig. 48, cen. can.). 



The cyclostomatous ovieell in all cases observed, belongs to 

 one or other of the two kinds briefly described above. That is, 

 it is either an enlarged zooecium. gonoecium of Hincks ('80), or 

 what is often spoken of as an inflation of the surface of the 

 colony, gonocyst of Hincks. Even in the latter case, according 

 to Harmer, the ovieell arises in, or is in close connection with a 



