295 



No zooid-streak was visible. The polyps are very indistinct and occur on 

 both sides, though mainly on the upper surface of the pinnules. The polyp 

 region extends almost to the zooid-plate on the lower surface. Their position 

 can be locateil in many cases only by means of tlie mesenteries appearing 

 through the transparent walls. 



This sjjecies is distinguished from — 



{<i) /'. hreve, Kolliker, (1) by having only eight to ten rays instead of fifteen 

 to sixteen ; (2) by the narrow insertion of the pinnules ; (3) by the 

 fact that there are rudimentary pinnules at the lower end ; and (4) 

 inasmuch as the pinnules do not all stand straight out from the keel. 

 {h) P. pellacidam, Kolliker, (1) by the more sickle-shaped pinnules; (2) by 

 the general contour of the colony ; (3) by the long free s])a,ce on the 

 meta-rachidial surface ; and (4) in not having a broad polyjj-zone and 

 large polyps. It agrees with this species in the fact that both have 

 short spines at the pro-rachidial insertion of the pinnule. 

 {r) P. mac-andrewi , Kolliker, by the mode of origin of the rays in the 



pinnules. 

 Locality : Andamans. 



Pteroeides indicum, n. sp. 



A single large specimen of a light brown colour represents this species. 



Total length of colony 115 mm. 



Length of rachis 90 mm. 



Breadth of rachis 70 mm. 



Length of stalk 25 mm. 



Thickness of stalk . 9 nim. 



Number of pinnules 27 



Number of rays . 17 



Length of pro-rachidial margin of largest pinnule . 30 mm. 

 Breadth of insertion of largest pinnule . . .10 mm. 



Breadth of largest pinnule 21 mm. 



Distance between pinnules 12 mm. 



The zooid-plate is median and as there is no ventral cushion it falls into 

 Kolliker's pellucidum-group. 



The stalk is hard ; it is comparatively thin and has a swelling just below the 

 base of the rachis. The keel is much broader than the stalk and has the shape 

 of an elongated ellipse. The rind is tough and parchment-like but the interior 

 is spongy. The pinnules are developed laterally, but towards the base there 

 is a distinct shunting towards the pro-rachidial surface, the lowest pair being 

 separated by about 4 mm. They are fan-shaped and more distant (12 mm.) 



