178 



CEYLON PEARL OYSTER REPORT. 



-.. 



Acamptogorgia rubra, n. sp. Plate, fig. 5, and text-fig. 1. 



A deep crimson, incomplete colony, 5 centims. in height, giving off in one plane 

 three lateral branches which have an average thickness of about 1 niillim. There is 



also a fragment about 2 centims. in length, with four 

 twigs arising almost at right angles from the main branch, 

 which is slightly over 1 millim. in breadth. 



The verrucas, 0'5 millim. in height by 1 millim. in 

 breadth, are alternate or sub-opposite, and arise at right 

 angles to the axis. Two occur side by side at the end of 

 a branch. The coenenchyma is thin and presents a very 

 prickly appearance, due to the projecting folia and spines 

 of the beautiful crimson spicules. The axis is yellowish , 

 0*3 millim. to - 4 millim. in diameter. 



The spicules show considerable diversity of form : 



(a) Straight, warty spindles, - 6 millim. x 0*1 millim. ; 



(b) Narrow, curved spindles, smooth terminally, warty 

 about the middle, 0"6 millim. x 0'05 millim. 



(c) Large triradiate forms in which the shortest, almost 

 smooth ray projects externally and often bears a foliaceous 

 expansion, while the two larger rays are denticulate or 

 branched to a very varied degree ; 0'6 millim. in breadth 



between the tips of the longest rays and 0"4 millim. in height between a line joining 

 these internal tips and the tip of the external ray. 



(d) Smaller and often simpler triradiate forms, G"45 millim. in breadth and 

 0"25 millim. in height, and much smaller. 



(e) Small, very warty spindles with a foliaceous expansion about the middle, 

 0'2 millim. x 0"1 millim. 



Locality : Ceylon seas. 



Fig. 1. 

 Acamptogorgia rubra, n. sp. x 15 



Muricella complanata, Wright and Studer. 



Reference has already been made (Part III., p. 303) to varietal forms of this species, 

 which seem to vary considerably in detail. Another form deserves to be recorded. 

 It differs from the type in the coloration of the spicules, large yellowish spindles 

 covering smaller transparent ones, and others still smaller which are rose-coloured. 

 Thus the rubbed base of the specimen is bright rose, while the upper parts are 

 ochreous yellow a difference which seems to be wholly due to the degree of abrasion. 



The verruca? show the characteristic longitudinal grouping of small spindles in eight 

 triangles, but it may be noted that in some cases they occur opposite one another, 

 instead of alternately as in the type, and that the diameter of their base can hardly 

 be said to exceed a millimetre, while that in the type was 2 millims. 



