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 ray 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 
" difiiculties 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 fiUformis. Dr Carpenter, in his work, The Microscope 
and its Revelations," at page 559, gives a sketch of the hooked spine of 
the E uryale ; 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 
