ON THE DEVELOPMENT OF TUBULIPORA. 105 



the normal ooeciostome, whicli can be seen in the more proxi- 

 mal part of the ovicell. 



One of these cases is a small pyriform colony (fig. 2), be- 

 ginning with the usual primitive disc, which measures 185 /a 

 in diameter. One ovicell is present, with a normal ooecio- 

 stome, its tube (fig. 3) being long and to a large extent free, 

 and the ooeciopore measuring 265 u. To the apparent right 

 of the ooeciostome one of the lobes of the ovicell ends in an 

 accessory ooeciostome (fig. 2.l), 105 fi in diameter; while on 

 the other side three lobes have accessory ooeciostomes. Of 

 these, No. 2 measures 165 fx; No. 3 is not yet fully formed; 

 and No. 5 is 90 /z in diameter. A smaller tube (4), at the end 

 of a very small ovicell-lobe, had closed except for a minute 

 terminal pore. 



A second case is that of a portion of a larger colony. The 

 fragment is rather more than 2 mm. in transverse diameter, 

 and has five ovicell-lobes, each of which has an accessory ooecio- 

 stome, a normal one being present more proximally. One 

 of these closely resembles the normal ooeciostome, while 

 another has about the same diameter at its base, but then 

 becomes much constricted, finally opening by an orifice much 

 smaller than a normal orifice. 



I have not had time to examine sections of this species, but 

 it appears to me highly probable that the accessory ooecio- 

 stomes are functional in providing a means of escape for the 

 larvae which find their way into the lobes to which they 

 respectively belong. 



Tubulipora plumosa,^ W. Thompson (fig. 1). 



Tubulipora plumosa, W. Thompson, iu Johnston (20, p. 274 [immature]). 



Tubulipora phalaugea (part), Johnston (20, p. 273, especially the state- 

 ments given on the authority of Mr. Peach). 



1 Thompson's name first appeared in 1847. In the same year Keuss 

 (" Foss. Polyparien d. Wiener Tertiarbeckens," in Haidinger's ' Naturwiss. 

 Abhandl.,' Baud ii, Abth. 1, 1848, p. 39) described Defrancia pluma and 

 (p. 51) Diastopora plumula. The former, at any rate, is doubtless a 

 Tubulipora, and is given as a member of this genus by Manzoni ('Denkschr. 



