279 



converging lateral margins meet in an almost straight or slightly curved 

 margin. The well-chitinized operculum has on the other hand a broadly quad- 

 rangular, accessorial (tig. <S d) and within each lateral margin a short, slightly 

 curved muscular ridge. As in the j)receding species we find two large distal pore- 

 chambers bounded by the angularly beni distal wall, while each lateral wall has 

 3 — i communications with the neighbouring zou'cia. 



The ooecia (figs. 8 b, 8 c) occur in small numbers scattered among the zone- 

 cia, and the gonozocecia are provided with a large, broad, somewhat flat, lip- 

 shaped, obli([uely ascending expansion which is situated proximally to the aper- 

 ture. The latter is wholly or partly hidden by the expansion and its proximal 

 margin is slightly angularly bent. The operculum (fig. 8 f) has a small, com- 

 j)resscd process on either side. The strongly arched kenozooecia have a number 

 of scattered pores, which are however wanting in the steeply ascending portion 

 distally to the aperture and the projecting central portion of the frontal surface 

 is generally developed as an expansion, more or less sharj)ly delimited. 



As the form just-described dilfers in the want of a sinus in the poster of the 

 aperture from Lepralia hiidliiui, var. coniiita described and figured ))y Busk ' 

 1 originally felt inclined to consider them specifically dilTerenl in s|)ile of 

 llie corresponding development of expansions. But as I have had a later op- 

 portunity of examining an aj)parently closelj' related form from Victoria, the 

 aperture of which is provided with a well-developed sinus (fig. 9 b), I must 

 supi)ose all three forms to be varieties of one species, Hippothoa corniila Busk, 

 which is very variable, not least in the form of aperture. This variety may 

 be termed uporosa. The three expansions are of a similar form and structure 

 as in var. holostoiua, and the median expansion especially is provided (lig. a) 

 with a similar septum perforated by a pore. The gonozoa>cium (fig. 9 c) has a 

 similar lii)-shaped expansion, but its aperture, like the zoa^cial aperture, is pro- 

 vided with a narrow, deep sinus, lo which a process on the oi)erculuni (fig. 9 e) 

 corresponds. The kenozooecium, which to judge from the figure only possesses a 

 circle of marginal pores in Busk's form, is here at the outside furnished with a 

 few median pores and is even more strongly arched than in var. luilostoina, its 

 surface being very hunched. A small colony from Victoria has Ijcen found on 

 Plerocladia Incida in the herbarium of algtc in the Botanical Museum. 



2, p. 84, PI. \C\\ figs. 3—5. 



