132 W. M. Bale: 



Exp.. 4 ser.. vii.. 1907, p. 352; Bartlett, Geelong 



Naturalist, 2 ser., iii., 1907, p. 44. fig. — ; Warren, 



Ann. Nat. Gov't. Museum, i., 1908. p. 303, fig. 7, pi. 



xlvi.. figs. 23-26. 



Billard has pointed out that in this species there are not always 



three pairs of hydrothecae between every two pairs of pinnae, as 



stated in the original description, but that the number varies, three, 



however, being the rule. I have noticed a similar irregularity in 



a Portland specimen given to me by Mr. Maplestone, which has four 



pairs in some of the intervals, thus agreeing with the majority of 



cases in which Billard found a departure from the typical number. 



I have also met with a specimen in which the stem, consisting of 



thirteen internodes, Avas unbranched throughout. 



Warren mentions that liis Natal speciTnens were usually covered 

 with a delicate algal incrustation. This organism is also very com- 

 monly found on Australian specimens. 



S. pluridenfafa (Kii-chenpaiier), another African species, is re- 

 markably similar to the present in the general form of the hydro- 

 thecae. The pinnae, however, are not opposite, but, according tO' 

 Kirchenpauer. irregular. The denticulation of the hydrotheca- 

 bordfer appears to agree with tliat of S. acanfhontomn in so far that 

 it is symmeti-ical on the two sides of the hydrotheca, but the teeth 

 differ both in number and arrangement, S. acavthostoma having 

 sixteen, while <S'. pluridentata has only eight. These eight are 

 arranged precisely like those of many Statoplean Plumularians ; 

 that is to say, there is a median unpaired tooth on the adcauline 

 extremity of the border, and a similar one on the apocauline margin, 

 while each of the intermediate sides supports three teeth, thus 

 making two unpaired teeth and three pairs. In .S". acanfhnstoma 

 there are no median teeth on either the adcauline or the apocauline 

 margins, but the teeth are arranged in eight synunetrical pairs on 

 the tAvo sides. Warren's figure of the hydrotheca. seen from above, 

 presents a quite stiiking resemblance to the front view of llalivor- 

 narla iliciafoiiKt . in which also the teeth are airanged. some point- 

 ing iuAvard and others outAvard. 



Dr. Warren has furnished interesting details of the sti-ucture. 

 pointing out especially that in the concave depression at the outer 

 margin of the hydrothecii there is a thickening of the ectodermal" 

 epithelium. Avhich has very nuicli tlie character of a nematophore, 

 being provided with a l)atteiy of laige nematocysts similar to those- 

 found in the Plumularians. He also i-eitiarks that the hydrotheca, 

 is distinguished by possessing no trace of openulum. 



