RIJKS MUSEUM VAN NATUURLIJKE HISTORIE — LEIDEN. 215 



XVI. — FOUR SPECIMENS OF PTEROEIDES STEENSTRUPII 

 KÖLLIKER COLLECTED BY P. BUITENDIJK, TANDJONG PRIOR 1907. 

 BY Prof. Dr. S. J. HICKSON. 



There are 4 specimens with the following measurements in length: 

 specimen A. 280 mm. specimen C. 100 mm. 



„ B. 150 , „ D. 90 „ 



The largest of these has fully developed leaves with a marginal 

 length of about 40 mm. 



In specimen B the leaves are represented by broad triangular lobes 

 having a maximum marginal length of 5 mm. 



In specimen C the leaves are also remarkably small but larger than 

 in specimen B. 



In specimen D, the smallest of the series, the leaves are still larger 

 having a maximum marginal length of 10 mm. 



It is evident, I think, that of these four specimens only one (speci- 

 men A) is normal. The others have either been injured or have under- 

 gone some pathological change. 



It is difficult to understand what kind of injury the specimens could 

 have undergone which destroyed all the leaves and left the rachis intact 

 unless they were attacked by some carnivorous fish that had a partiality 

 for the leaves. It is however extremely improbable that Pteroeides is 

 preyed upon by any carnivorous animal. I have examined a very large 

 number of specimens of the genus from different parts of the world and 

 have never seen any injury to. the leaves that could be attributed to fish 

 bites. The only Pennatulacean that has been found in the stomach of 

 fish is Virgularia, a genus which has no spicules in any part of the 

 leaves or rachis; and there is no evidence that any other genus of 

 Pennatulacea is attacked by fish or any other carnivorous animals. The 

 condition of the three specimens therefore is not in my opinion due to injury. 



A microscopical examination of the leaves of the specimen B, does 

 not afford any evidence of active regeneration of the tissues. The 

 superficial epithelium is missing and endoderm cells of the zooids and 

 canals are apparently free or coagulated into lumps. The appearance 

 in the section is that of a tissue that is either very badly preserved 

 or moribund. The conclusion therefore is that the three specimens B, C 

 and D were moribund when captured and that their leaves have been 

 almost completely macerated and lost. 



