Mr. S. O. Kidley on Sponges. 187 



bundles of spiculo-fibre are not so well marked as in the 

 cerebriform variety. 



Spirastrella j)ulvinata. 

 Hymeniacidon pulvhiata, Bowerbanli, P. Z. S. 1872, p. 126. 

 As the spiculation and other characters of this species agree 

 with those of Schmidt's genus Spirastrella, I have labelled 

 the magnificent specimens on which the species is based, now 

 in the British Museum, as above. 



Tetractinelli da. 



CoralUstes parasitica. 



■ Arabeseula parasitica, Carter, Ann. & Mag. Nat. Hist. 1873, xii. 

 p. 464. 



An immense specimen, about 19 inches wide, 11 inches 

 high, was acquired for the National Collection from Maui'i- 

 tius some little time since. It has the general form of a single 

 somewhat folded cabbage-leaf. It is attached by a short 

 distinct submedian stem, 35 millim. high, 75 millim. wide 

 across the front, 35 millim. from back to front; the frond 

 itself ranges from 10 to 15 millim. in thickness. When 

 perfect, the greater part of the margin appears to have been 

 sharp, and uninjured remains of it have a pinched-up ap- 

 pearance. 



When attached, the frond probably was suberect, the upper 

 half being recurved so as to form an angle of about 60° with 

 the basal portion. The whole of that side which thus becomes 

 the upper side is beset with small conical vents, about 1 millim. 

 high,*6-l millim. wide at their mouth, distributed at intervals 

 of from 2 to 4 millim. ; in most cases they may be seen to be 

 entered, at about 1 millim. below their margins, by a number 

 of secondary excretory canals. The opposite surface of the 

 frond is covered with similar but smaller openings, slightly 

 prominent, about '3 millim. wide at the mouth, arranged in 

 sinuous series, about 1 millim. apart, the openings of those of 

 the same series being almost in contact with each other. The 

 external and minute characters of this fine species, now that 

 they are fully known, agree well with those of CoralUstes. To 

 Carter's account of the spicules may be added that a flesh- 

 spicule, bow-shaped or somewhat sinuous, minutely roughened, 

 and measuring "OlO millim. long by '0017 millim. thick, occurs 

 very abundantly in the dermis. 



15* 



