HARDWICKE'S SCIENCE-GOSSIP. 



SI 



frequent than T. scorodonia. FJovvers somewhat like 

 but corolla tubes shorter and inflorescence different. 

 Trifoliuiii moii/aitum and riihntm, banks. Viola 

 mirabilis, bushy places. 



E. DE Crespignv. 



{To be continued.) 



OPHIOCOMA NEGLECTA. 



EVERY ONE who has ever been down to the 

 seashore, and made use of his eyes as he has 

 wandered among the rockpools, knows what a brittle 

 star is — an odd-looking creature indeed, unlike any- 

 thing to be met with in the fields and hedgerows, 

 unless we conceive five lively centipedes with their 

 tails tied into a Gordian knot, all persistently en- 

 deavouring to free themselves. But even as "there 

 be land rats and water rats," so are there brittle 

 stars and sand stars ; and possibly the majority of 

 persons to whom these are by no means unfamiliar 

 objects, would on finding a specimen be a little 

 puzzled to say, to which section it belonged. Now, 

 as a matter of fact, they are very easily distinguished. 

 In Ophiura (sand star) the rays are prolonged into 

 the disc on the upper side, or, in other words, the 

 periphery of the disc is interrupted by the insertion 

 of the rays ; in Ophiocoma (brittle star) the rays are 

 not prolonged into the disc, therefore the periphery 

 is entire. On the under side the distinction is even 

 more evident : at the junction of the rays, alternating 

 with and separating them, there are five scale-like 

 plates. These plates in Ophiura are large and con- 

 spicuous, rather narrow and shield-shaped ; in Ophio- 

 coma they are small, short, broad, and somewhat 

 pentagonal. Only two British Ophiurje are known, 

 whilst Ophiocoma is represented by ten or twelve 

 indigenous species. Of the latter genus the most 

 common, in fact the brittle star par excellettce, is 

 O. rosula. It is extremely variable in colour, and 

 some of the varieties are remarkably pretty. 



Less generally known, though probably scarcely 

 less abundant, at least along the southern coast, is 

 Ophiocoma ncglccta, a diminutive species with rays 

 half an inch long at most, and a disc not more than 

 one-sixth of an inch in diameter in adult specimens. 

 They are easily overlooked, although in favourable 

 localities often abounding among the corallines and 

 small algte that fringe the rockpools, as well as 

 under stones. Sometimes you will find them in a 

 tangled mass of Laminaria which has been fiercely 

 wrenched from its ocean bed in the mighty struggle 

 between wind and waves and cast upon the beach. 

 At Lymington, in Hampshire, almost close under the 

 sea-wall, at the higher part of the mud-flats which 

 stretch out far into the Solent, I used to find 0. 

 neglecta in such vast profusion that I believe I could 

 have collected several hundreds in a very short time. 

 They appeared to have a strong predilection for 



Fiicus vesictilosiis, which certainly looked remarkably 

 uninviting and unwholesome just there, and I have 

 seen on a single slimy, mud-coated plant quite fifty 

 specimens of this little brittle star of all sizes, from 

 full-grown individuals down to tiny little fellows 

 scarcely visible without a lens. 



Now I strongly suspect that, microscopically speak- 

 ing, the specific name of this Ophiocoma is vastly 

 appropriate ; and in writing these notes my desire 

 is simply to direct to it the attention of those readers 

 of Science-Gossip belonging to that large class of 

 unpretending, but sincere microscopists who having 

 neither opportunity nor leisure for "taking up a 

 subject and going deeply into it," are always glad 

 to add somewhat to their stock of knowledge con- 

 cerning the common objects of the seashore, and to 

 take home an interesting and instructive souvenir of 

 a summer holiday at the seaside. 



No British echinoderm will so well repay the 

 trouble of mounting as Ophiocoma neglecta, for, owing 

 to its small size, even full-grown specimens may be 

 displayed on a slide of ordinary dimensions. I would 

 recommend, however, the selection of medium-sized 

 individuals, because the larger ones have mostly been 

 "in the wars," and have suffered in consequence. 

 Kill the specimen by immersion in fresh water for 

 a minute or two, then transfer it to a little saucer 

 of liquor potassae, where it must be allowed to remain 

 for some hours ; the length of time has to be deter- 

 mined by experiment : if too short, the mucus will 

 not have been dissolved, and if too long the limbs 

 will be tender, and readily part company. The 

 smaller the specimens, the less time must they remain 

 in potash. Wash well, and mount in balsam. When 

 examined under a low power, either with or without 

 dark field illumination, few objects will prove more 

 attractive both to scientific and non-scientific ob- 

 servers. The lower side of the disc, detached from 

 the upper, with the rays severed^at their insertion, 

 is strikingly beautiful, and shows the oral aperture 

 with its surrounding plates ; while the upper side, 

 treated in the same way, exhibits the rosulate ar- 

 rangement of the scales and the characteristic gemi- 

 nate plates which lie at the base of the rays. The 

 form and relative position of these large geminate 

 plates are of the utmost value in discriminating the 

 various species of Ophiocoma ; in fact they constitute 

 one of the main specific characters. O. rosiila and 

 O. neglecta are the only two in which these plates are 

 contiguous throughout their length — in the former 

 they are triangular, in the latter oblong. One of the 

 rays of a large specimen, when a perfect one is 

 selected, should also be mounted singly, as it may 

 be made to show the arrangement of the scales and 

 spines better than in an entire specimen. 



Nor have we even yet, in these various preparations, 

 discovered all the points of loveliness that ornament 

 this tiny denizen of the deep. Quite unsuspected, 

 and therefore the more surprising, Js the diversity of 



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