PEXXATULIDA OF THE MERGTJI ABCHIPELAGO. 269 



uniform diameter. The general colour is brownish yellow 

 mottled with purplish spots, especially near the edge of the 

 leaves. The axis extends the whole length of the colony, is mode- 

 rately flexible, and hooked at both ends. 



The top of the rachis projects about 4 mill inn, beyond the 

 uppermost leaf, and bears on its dorsal surface a longitudinal row 

 of four small rudimentary polypes, which probably represent the 

 dorsal zooid stripe of other species. 



The leaves are small, and directed upwards, overlapping one 

 another like tiles. The largest ones are a little above the middle 

 of the rachis : the uppermost two or three pairs are small and 

 very stiff : in the lower half of the rachis the leaves gradually 

 diminish in size, but retain their lateral position. The leaves are 

 fan-shaped, the free dorsal border sometimes nearly straight as 

 though truncated, sometimes irregularly notched. The rays are 

 broad, 11 in number as a rule, and very conspicuous on the 

 under surfaces of the leaves ; their distal ends project as short 

 irregularly placed spines. The polypes or autozooids are small, 

 and arranged in 4 or 5 rows along the edge of each leaf and on 

 both surfaces. There is a prominent, sharply defined basal zooid 

 plate, which does not touch the zone of the autozooids, and is 

 yellow in colour. There is no ventral zooid stripe. Small calca- 

 reous needles are present in considerable numbers in the leaves, 

 round the bases of the autozooids, but there are no spicules in 

 the cutis of either the rachis or stalk. 



The principal dimensions of the specimen are given below ; for 

 the sake of comparison the measurements as recorded by 

 Kolliker of the specimen in the Leyden Museum are also given. 





Andaman Island 

 specimen. 



Specimen in 

 Leyden Museum. 



Length of colony 



165 



203 





57 



38 





108 



154 





10 



10-12 





5 



65 





5-5 



8 





right side 34+8 



right side 40+6 



left side 39 +13 



left side 43+8 



Height of largest leaf 



8 



Ventral border of largest leaf 



8 



11 



Base of attachment of largest leaf 



4 



5 





11-12 







Oto -5 





23* 



