6 PROFESSOR J. A. THOMSON AND MR JAMES RITCHIE 



variable number of polyps in a whorl is of greater importance, but it probably means 

 nothing more than a greater vigour of growth. 



The figure in the Challenger Report shows the whorls too far apart, as the text 

 points out ; we have therefore given a supplementary figure. 



Locality. Burdwood Bank, lat. 54 25' S., long. 57 32' W. ; 52 fathoms. Surface 

 temperature 40 '8, December 1, 1903. 



Family MURICEID^E. 

 Paramuncea robusta, n. sp., PI. I. fig. 6 ; PI. II. figs. 2 and 7. 



A strong upright colony of a light brown colour, expanded for the most part in 

 one plane, 27 '5 cm. in maximum height by 14 cm. in maximum breadth. Not far 

 from the base, which is expanded to 2 cm. and soon narrows to 1 cm., a strong 

 side-branch is given off with a diameter of 6 mm., and this, like the main stem, bears 

 strong offshoots from which smaller, usually simple, branches arise. The branching 

 is very irregular, but anastomosis is rare, being represented in one of the specimens by 

 only two instances, one of which shows the junction of an apparently broken branch of 

 the first degree with the main stem. In another specimen, 18 cm. by 12 cm., there is no 

 anastomosis. Towards the base of the colony the main stem is distinctly flattened, 9'5 

 by 8 mm., immediately above the basal thickening. 



The axis is horny, non-calcareous, fibrous, and of a brownish colour. It narrows 

 from about 6 mm. near the base to 1 mm. near the tips of the branches. 



The coenenchyma is relatively thin (0'5 mm.) and somewhat translucent, allowing 

 the brownish axis to shine faintly through. Its surface is rough, owing to the abundance 

 of large colourless spicules which cover it. Some of these spicules project from the 

 tops of the verrucse as crowns of spines. 



The yellowish verrucee are cylindrical with a slightly conical summit, 1'5 mm. in 

 height by 1 mm. in diameter, and arise perpendicularly from all sides of the main stem 

 and its branches. They are closely set, without any regular interval between them. 

 Four or five are always grouped at the tip of a branch, giving it a knobbed 

 appearance. 



The polyps are wholly retracted, and an operculum of 8 parts, each composed of 

 about 5 spicules resting on the bases of the tentacles, closes over the aperture. Round 

 the top of the verruca a few rows of spicules are arranged horizontally, and on this 

 support the bases of the opercular covering rest. 



Various types of spicules characterise the species. Most characteristic are the large 

 tuberculate clubs whose ' handles ' form the spiny crowns of the verrucre, while the much 

 divided root-like ' heads ' are embedded in the coenenchyma. There are also simpler clubs 

 with heads covered with tubercles and spiny processes. Curved spindles are common, 

 some knobbed and thickened, with comparatively large projecting processes and smaller 



(ROY. sor. EWX. THAXS., VOL. XLI., 856.) 



