ON A NEW SIPHONOGORGID GENUS CACTOGORGIA. 831 



bear a distinct " crown and points " armature visible to the naked eye ; " the crown " 

 consists of 10-14 rows of curved spindles ; the " points " are composed of 10-15 spicules 

 slightly "en chevron." The spicules are transparent: (A) those of the stem and 

 polyparium are warty spindles ; (B) those of the anthocodise are spiny spindles and 

 clubs ; (C) those on the tentacles are scale-like sclerites. The following are average 

 measurements length by breadth in millimetres: — (A) l'6x0'45; 0'6x0'15. (B) 

 1-2 x 0-1 ; 0-5 x 0-05. (C) 012 x 0"02 ; 0'04 x 0'02. 



Distribution. 



All the specimens are from the Indian Ocean, and seem to be of a semi-littoral 

 nature. C. celosioides, n. sp., is recorded from the Andamans (depth uncertain) ; 

 C. expansa, n. sp., was dredged off Cape Comorin in 38 fathoms; while C. alciformis, 

 n. sp., occurs both at the Andamans and off the Arakan coast ; at the latter place it was 

 found in 13 fathoms. 



More Detailed Description. 



Owing to the denseness of the spiculation and the consequent damage in decalcifica- 

 tion, it was impossible to investigate the histology of these specimens ; but the following 

 more detailed descriptions may give some basis and justification for ranking them under 

 a new and distinct genus. 



Cactogorgia celosioides, n. g. et sp. (figs. 1, 2, 3a, 3b, 3c). 



This species is represented by two small specimens of a light brown colour. They 

 present a characteristic appearance, which suggests in many respects the structure of the 

 coxcomb (Celosia). Both specimens are attached by a slightly expanded disc to pieces 

 of detached rock. The first has a cylindrical stalk 16 millims. in length and 6 millims. 

 in diameter, but expanded at the disc of attachment to 1 millims. ; this is surmounted 

 by an upper polyp-bearing portion flattened in one plane and almost semicircular in 

 outline; it is 20 millims. in length and 19 millims. in breadth just above its insertion 

 on the stalk. The second specimen (fig. 2) has a more irregular contour. The barren 

 stem is also flattened in the plane of expansion of the polyparium ; it is 17 millims. in 

 length and 11 millims. in breadth, and supports a polyp-bearing portion 19 millims in 

 height and 16 millims. in breadth. From the base of the stem an offshoot or lobe 

 8 millims. in height and 9 millims. in breadth is separated by a constriction, and this 

 part also bears polyps almost over the entire hemispherical head. 



Both the colonies are stiff and rigid, owing to the dense network of large warty 

 spindles, which are quite visible to the naked eye. These are arranged for the most 

 part longitudinally, and their transparency gives the whole a translucent sheen. 



