70 THE VOYAGE OF H.M.S. CHALLENGER. 



Var. c. gracilis. 



A very elegant, finely ramified form. The stem is 140 mm. long and is thin and 

 flexible; it has at the base a diameter of I'S mm.; at first firm and brittle, it soon becomes 

 horny and flexible. The twigs have at the base a diameter of 0'5 mm. and soon give 

 ofi" lateral twigs, usually 2 to 3 mm. long. These are always simple, thin, their length 

 reaching 10 to 15 mm. The twigs are developed to about the same extent throughout 

 the whole colony, only towards the apex they are shorter, they come ofl" symmetrically on 

 the three sides, and are bent at the ends, so that the colony acquires quite the appear- 

 ance of a plume. 



The polyps are placed on the twigs in close spirals of threes, they are cup-shaped and 

 2 mm. long. 



The scales of the calyx form five transverse rows, those of the last and last but one 

 develop spines, which form a crown around the calyx mouth and may completely cover 

 the opercular scales, yet they never develop to the length of those of the type. 



Spicules. — Calyx scales large, those of the uppermost row, rhombic or triangular, 

 with a long spine, which is the continuation of a median keel radiating from the 

 nucleus and projecting from the scale. Height to breadth, 0'62 to 0'32, the spine takes 

 up 0-25 ; 0-36-0-36 to 0-68-0-25 mm. The succeeding scales are broad, but possess 

 also a median keel and a short serrated spine. Height to breadth, 05-0 "42 ; 0"45- 

 0"33 mm. The lowest scales are without the spine, but are strongly serrated on the 

 upper edge, 0-33-0-5; 0-41-0'4 mm. 



The opercular scales are small and high, triangular, deeply furrowed in the middle 

 line. Height to breadth, 05-0 '2 mm. 



The scales of the coenenchyma are in the upper layer irregularly polygonal to four- 

 cornered, on the free edge sharply serrated, with an excentric, but sometimes a marginal 

 nucleus. Height to breadth— 0-37-0-4 ; 0-22-0-3 ; 0-25-0-31 mm. Those of the lower 

 layer are thin lamellae with fine warts, four-cornered or irregular, provided with processes 

 O-l-O-ll ; 0-1-0-14 mm. 



Habitat. — Station 150, ofi" Heard Island; depth, 150 fathoms ; bottom, coarse gravel. 



Genus 6. Amphilaphis, n. gen.' 



Colony generally ramified in one plane. Branches dividing ofi" from the main stem 

 on two sides in alternating series ; these either remain simple or give ofi" simple lateral 

 twigs. Branches as well as twigs run parallel to one another, coming ofi" from the stem 

 or the branches, at angles of about 45°. The club-shaped polyps arise at varying intervals 

 from one another in the circumference of the stem, of the branches and of the twigs, 

 originating mainly from four difi"erent sides of the periphery. The scales of the calyces 



■ ii/^(pi, T^etpis, dividing into branches. 



