ALC YON ARIA. 343 



rupted, and accompanied by raised margins); near their origin 

 some of the chief pinna) show similar furrows at their bases, ex- 

 tending some distance upwards in those which have themselves 

 becomo pinnate. These grooves may be replaced in parts of the 

 specimen* by irregular raised lines. Verruca; disi ributed with more 

 or less regularity in two alternating rows down each lateral face 

 of the branches and the pinnae (often uniserial in young specimens), 

 in number from 18 to 30 to an inch on each side; they appear 

 as low, gradually elevated prominences, often barely elevated, but 

 most so near the tips of the pinna) ; the mouth is formed by a 

 longitudinal slit extended in the direction of tho long axis of the 

 branch. Cortex about -6 millim. thick on main stem. Axis black 

 in stem, filiform, transparent, and pale brown at tips of pinnae. 

 Spicules fusiform, long or short, beset with prominent tubercles 

 arranged in whorls in the median portion of tho spicule, massed 

 together at the ends ; whorls separated by more or less distinct 

 bare spaces ; about 8 whorls in long fusiform spicules, 4 in stout 

 ones ; tubercles fungiform, consisting of a cylindrical base with an 

 expanded and roughened apex. Spicules either lemon-yellow, 

 chrome-yellow, deep crimson, or (rarely) partly crimson and partly 

 yellow or colourless. Dimensions (average maximum f) : — 



millim. millim. 



i. Loug fusiform spicules . . -152 by -038 to -177 by -038 to -044. 

 ii. Stout fusiform spicules .. -108 by -05 to '127 by -041. 

 iii. Verruca-spicules(fusiform) -139 by -031 to -140 by -032. 



No other forms of spicule observed. 



Two forms of this species may be distinguished : — 



(1) Yar. fiavotincta. Stem, main branches, and bases of pinnae 

 of pale brownish-yellow colour, inclining to crimson-red in the 

 neighbourhood of the cells ; the latter colour characterizes the re- 

 maining parts of the pinna) and becomes deeper towards their apices; 

 the paler tints are due to the intermixture of crimson and yellow 

 spicules ; the ends of the pinna) possess crimson spicules only. The 

 spicules measure — (i.) long fusiforms -177 by -038; (ii.) stout 

 fusiforms -127 by -041 ; (iii.) verruca-spicules -142 by -038 millim. 



(2) Var. perfiava. Whole corallum bright yellow, being lemon- 

 yellow in one specimen and chrome-yellow in another. The spi- 

 cules are almost all of a bright yellow colour, some of a darker tint 

 than others ; a crimson one is occasionally to be found. Dimensions 

 (average greatest) : — 



Chrome-yellow specimen. Lemon-yellow specimen, 

 millim. millim. 



i. Long fusiform .... -165 by -044. -152 by -038. 



ii. Stout fusiform .... -12 by -05. -108 by -05. 



iii. Verruca-spicule . . -146 by '032. -139 by -031. 



* Perhaps due, as also the variations in the grooves, to wrinkling of the 

 cortex during the process of drying. 



t The endeavour has been to arrive at the size of the adult spicule in each 

 case, by a series of comparative measurements ; the variations here given are 

 those occurring in different specimens. 



