270 PEOF. MARSHALL AND MR. G. H. FOWLEE ON THE 



Pteroeides Laoazii, Kolliker. (Plate XXII. figs. 3-6.) 



Of this extremely variable species there are 34 specimens in 

 the collection ; 22 from the Andaman Islands, 12 from the 

 Mergui Archipelago. These differ a good deal among themselves, 

 but fall into two well-marked divisions, which we propose to 

 describe as varieties a and /3 respectively. 



Pt. LACAzir, var. a. (Plate XXII. fig. 3.) 



This group, which includes 21 of the specimens from the 

 Andaman Islands, is characterized by the following points : — 



The feather is narrower than in variety /3, and is of nearly 

 uniform width along the greater part of its length. The leaves 

 are more falciform in shape ; the rays are less numorous, but 

 stronger and more regularly arranged ; the spines are longer, 

 and the margin of the leaf more deeply notched. 



The principal dimensions of this variety are as follows : — 



— 



a. 



b. 



c. 



d. 





150 



237 



174 



163 





75 



97 



78 



87 





75 



140 



96 



76 





48 



47 



37 



33 



Width of rachis, ventral surface... 



17-5 



16 



10-5 



11 





12 



12 



10 



9 





40 +4 rud. 



47-1-4 rud. 



39 +7 rud. 



41 +7 rud. 





13 



20 



11 



10 





19 



18 



17 



14 



liase of attachment of largest leaf 







9 



4 



4 





15 



16 



13 



11-12 





2-2-5 



1-5-3 



07-2 



1-5-3 



Pt. Lacazii, var. /3. (Plate XXII. figs. 4-G.) 



The second variety includes the 12 specimens from the Mergui 

 A rchipelago, and one from the Andaman Islands. 



In these the feather is oval in shape, being widest at or slightly 

 above its middle. The leaves are fan-shaped, and softer than in 

 rariety «. The rays arc rather more numerous, but hardly pro- 

 ject beyond the margin of the leaf, which is almost entire, and 

 fringed witli short spicules. The stalk is markedly thicker than 

 in variety a. 



The principal dimensions of this variety are as follows:— 



