On Peculiar Forms of Spines in Star-Fishes. 



63 



posed in two rows. In Eudendrium the body of the polyp is 

 studded by very large thread-cells ; in Garveia these thread- 

 cells are absent. 



V. On some Peculiar Forms of Spines on two Species of Star- Fishes 

 (Gen. Ophiocoma). (Drawings were exhibited.) By Charles W. 

 Peach, Esq., "Wick. 



During my residence at Peterhead, I met with a very delicate Ophio- 

 coma,— probably 0. neglecta, — which I was very desirous of naming. 

 For this purpose I placed it alive in sea-water under the microscope, and 

 found that one of the spines had a notch of some width running down 

 the whole length of it ; this, I thought, had been caused by accident. 

 On farther examination, I found that each lower spine had a similar 

 opening ; — the edges of the openings serrated, the whole covered with 

 short pointed protuberances. I also saw the pinnated cirrhus protruded, 

 as at A, fig. 1, of the sketch exhibited. Not finding this notch 

 mentioned by Forbes, or any other writer on star-fishes, I have been 

 led to examine others, and have been rewarded by finding on the brittle 

 star, Ophiocoma rosula of Forbes, in addition to the " beautiful long 

 tapering rough spine," which, he said, "might serve as a model for the 

 spire of a cathedral," on the under side of each row a jaw-like hooked 

 one furnished with teeth (sketch No. 2) ; they are transparent, and 

 formed of the same material as the other spines. These jaw-like spines 

 extend the whole length of the rays, and are arranged (as at fig. 2, 

 where the tip and two of the under sides of the ray-plates are repre- 

 sented) with the spines and cirrhi. Two of the straight spines of each 

 group have also hooks on their tips, directed, as are the teeth of the 

 jaw-like ones, towards the disk. No. 3 is a side-view of a jaw-like 

 spine. I have seen these jaw-like spines on specimens in all stages 

 of growth, some not one-fourth of an inch over. There are many other 

 things as well as these spines that I might call your attention to, would 

 time permit. When describing Ophiocoma Goodsiri, Forbes mentions 

 " difficulties connected with the tracing of the connection between species 

 and species ;" and though he found in 0. Goodsiri " a beautiful link be- 

 tween the scaly and plated brittle stars," he farther says, " Before I saw 

 this species, I had some doubts as to the propriety of retaining these two 

 variations of character in the one genus, and suspected that Ophiocoma 

 rosula might be the type of a separate group." Had he seen these jaw- 

 like spines, he would, I think, have separated it, especially as at page 

 20 he farther says, — " the sources of specific character are derived from 

 the spines of the body and arms." In his work, the only hooked spines 

 mentioned are those found on Comatula rosacea, and the pick-like one 

 on Ophiocoma filiformis. Dr Carpenter, in his work, " The Microscope 

 and its Revelations," at page 559, gives a sketch of the hooked spine of 

 the Euryale ; and now, in all probability, the true connection between it 

 and Ophiocoma rosula will be better seen. These observations were 

 made on specimens found at Peterhead and Wick, N.B. I have since 

 had Ophiocoma rosula from Mr King of Torquay, Devonshire. Dr 

 Dickie of Belfast has also kindly sent me it from Ireland. All show 



