1906.] ALCYOXARIANS FROM ZANZIBAR. 437 



Ft- ffijly YlUGULARIID^. 



YiRGULARiA MiRABiLTS Laiiiouroux, var. PEDUXCULATA Kolliker. 



The rachis is 172 mm. in length, but the upper part (for 

 51 mm.) consists of nothing but the axis, which tapers to a fine 

 thread. The axis is 0"42 mm. in diameter, brownish in colour, 

 and marked by a large nvmiber of parallel transverse strife. 

 Towards the upper end of the uu weathered part of the rachis 

 the transparent pinnules are very closely packed together and 

 smaller than those on the lower part of the rachis. They are 

 separated from one another by intervals of 0"8 mm., and vary in 

 breadth from 0*9-1 '05 mm. and in height from 0"6-0'7 mm. 



On each pinnule there are six or seven polyps in a single row. 

 There is a clear streak on both rachidial surfaces of the rachis, 

 but that on the prorachidial siirface is slightly wider and has a 

 groove running up the middle. The coenenchyma is thin and 

 transparent, allowing the axis to shine through on both surfaces. 



Locality. Kokotoni, Zanzibar Island. In the mud at ordinary 

 low- tide level. Previously recorded from Scandinavia, Denmark, 

 Iceland, and Gulf of St. Lawrence. 



ViRGULARiA MULTicALYCiNA, sp. n. (Plate XXVI. figs. 4 & 5.) 



A well-preserved portion of a colony, probably near the tip. 

 It has a light brown colour, and was described when living as 

 " black and light drab." In a length of 22 millims. there are on 

 each side 11 pinnules, each about 2'25 mm. in height, and bearing 

 about 66 polyps in 2-4 rows. The breadth of the vane is 8 mm., 

 that of the axis 1'35. On the prorachidial surface there is a bare 

 streak 2'5 mm. in bi^eadth, with a median longitudinal groove. 

 At the insertion of each pinnule there is a superficial ramification 

 of the nutritive canal, forming a characteristic pattern. The 

 metarachidial surface has also a bare streak, but this is entirely 

 hidden by the interlocking of the pinnules, which form a quite 

 continuous covering over the whole of that surface. 



Very characteristic is the undulatory cui-vature of the margin 

 of the pinnule ; the ends of the insertion are on about the same 

 level on the prorachidial and metarachidial surfaces. The calices 

 are very distinct, barrel-shaped with narrowed mouths and longi- 

 tudinal ridges. A polyp with expanded tentacles is 1'25 mm. in 

 length, the calyx occupying about 0*9 mm. 



On the prorachidial surface numerous minute zooids are to be 

 seen, but no definite arrangement is recognisable. The shape of 

 the axis is peculiar. The cross-section shows an irregular quadri- 

 lateral figure; the longest (metarachidial) side is 1"35 mm. in 

 length and is slightly concave, the prorachidial side is 0*75 mm., 

 and the two parachidial sides are slightly convex and about 

 0-75 mm. in length. On the surface of the axis there are longi- 

 tudinally elongated elevations like interrupted ridges. 



This species resembles F. rwmphii Kolliker in the close-set 

 pinnules, in the crowded polyps, in the branching of the nutritive 



29* 



