290 SIDNEY F. HAiniKU'. 



The luinon of the spine has a characteristic globular dilatation 

 at the point where it crosses the calcareous ring. The 

 calcareous wall of this dilatation is completed externally by 

 the outer wall of the zooecium. The bases of the spines are 

 connected with one another by a thin calcareous web, while 

 ]iart of the frontnl membrane may project just beyond the web, 

 internal to the bases of the spines. 



The zooecia are arranged back to back in pairs, new 

 zocecia {z.') originating from the axial side of their distal end. 

 The orifice is close to this region, on the axial side of the 

 frontal wall (fig. 5). The occlusor muscles (occl.) originate 

 from the lateral walls. In correlation with the reduction of 

 the length of the frontal membrane, there is but a single pair 

 of parietal muscles {ji. m.). 



Bicellaria grandis, Busk, var. producta, MacGilli- 

 vray^ (fig. 1). — This is another example of an infundibuli- 

 form zoncciura. The frontal membrane is obliquely placed, 

 and is of restricted extent. The orifice is at the extreme 

 outer end of the membrane, and the zooocium is prolonged 

 beyond it into a lobe which bears three or four very long 

 spines. On the axial side of the zocBcium is a calcareous 

 thickening^ which surrounds the communication-pores (cj).). 

 The zooecia have the alternate arrangement characteristic 

 of the genus, and in most cases the calcareous thicken- 

 ing includes two sharply marked rings, one for the alternate 

 zooecium of the other side of the branch, and the other for 

 the next zooecium on the distal side. In fig. 1, however, 

 there are three calcareous rings, the zoocciuui being the one 

 which precedes a bifurcation, and having consequently to 

 give rise to two distal zooecia. A peculiarity of this species, 

 which I have not found in other species of Bicellaria, is 

 that the proximal part of the " aperture " becomes filled in 

 with a thin calcareous film (cryjjt.) which ends in a hook-like 

 point. I am unable to state with certainty what is the 

 function of this lujok, but I think that its distal edge forms 



' ' J'mdr. Zool. Vicl.,' Dec. vi, 1881, p. 38. 



- (^f. (joklslcin, ' Traus. Proc. Roy. Soc. Vict../ xviii, p. 48. 



