Nov. 1, 1S6S.3 



HABDWICKE'S SCIENCE-GOSSIP. 



2-17 



always remained at the bottom of the water. They, 

 like the pupae, move about principally by squirting 

 water out of the abdomen, and this faculty enables 

 them to conceal themselves quickly, after each 

 change of position they make ; for the flow of water 

 from the abdomen causes a gentle stream to pass 

 over them, which, carrying with it particles of mud, 

 soon covers them sufficiently to make it difficult to 

 distinguish them from surrounding objects. 



The observing of this pupa all through the winter 

 gave me and my family a great deal of amusement ; 

 and if any of the readers of Science-Gossip should 

 wish to follow the example, and should be fortunate 

 enough to witness the final change of the pupa into 

 the Dragon-fly, I think they will be inclined to 

 admit with me, that few sights in nature are more 

 wonderful and beautiful : the only piece of advice 

 I should give them would be, to keep the pupa in 

 a place by himself, as he will certainly look upon 

 almost all things put in with him as part of his 

 larder,- and treat them accordingly. 



Frederick. Pollock. 



Thurlow, Clapham. 



A ERESH-WATEB. ACTINIA. 



T) Y the courtesy of Dr. Stolicza, of Bengal, I have 

 -**' been favoured with some particulars, possess- 

 ing remarkable scientific interest, of the habits and 

 anatomy of what must be called a /Ska-anemone, 

 though it inhabits waters which are much more fresh 

 than salt. 



At a meeting of the Asiatic Society of Bengal 

 (see Proceedings for July, 1868) Dr. Stolicza com- 

 municated the results of his examination of the 

 anatomy of Sagartia Schilleriana ; a species of 

 Actinia, which he had found in the brackish waters 

 of the Sunderbunds, that low-lying district of India 

 that is formed by the numerous mouths of the 

 Ganges up which the tides flow. The species lives 

 attached to the trunks of old trees, in water which, 

 by analysis, contains not more than one-third of the 

 saline constituents of pure sea-water, in 1,000 parts 

 of which they vary from 32 to 37 parts. In general, 

 however, all the principal constituents, — the 

 chlorides, iodides, &c, are present ; the difference 

 affecting only the quantity, not the quality. 



The species is one of extreme softness and trans- 

 parency ; of a dull whitish hue, the column marked 

 with longitudinal, alternating greenish bands ; the 

 septa are usually 48 in number; the ovaria are 

 bluish-purple ; the craspeda yellowish or greyish 

 white, and the acontia pure white. The walls of 

 the body consist of five different layers ; the out- 

 most is a mucus, chiefly composed of large ctiidce or 

 nettling-cells, and a few pale-green pigment-cells. 

 Then follows a thin muscular layer, principally com- 

 posed of concentric or cross fibres ; next, a rather 



thick layer of green pigment ; then, again, a thick 

 muscular layer, gradually passing into a tough 

 muscular tissue, in which scleroids [or hard bodies] 

 of two kinds are imbedded. The one kind are long 

 cylindrical rods, with short lateral branches, and 

 consist of carbonate of lime ; the other kind are 

 thin flat rectangular plates of various forms, con- 

 sisting of silica. 



The nature of these scleroids, after their difference 

 of form had been observed by simple maceration of 

 the tissue, was positively ascertained by burning a 

 specimen of the animal in a platina crucible, until 

 all organic matter had disappeared. The result was 

 a perfect skeleton, represented by an irregular net- 

 work of solid white fibres. These were resolved, 

 by the usual chemical tests, into two portions, as 

 just stated ; the carbonate of lime, which formed the 

 larger portion, being dissolved away, left a very thin 

 membrane composed of the siliceous plates. 



The tentacles are arranged around or near the 

 margin of the disk, in apparently alternating circles, 

 and number about 150. The acontia, craspeda, and 

 ovaria are all attached to the internal side of the 

 strongly muscular larynx [or what I should term 

 the outer side ; for I presume that the surface of 

 the stomach-wall which is next to the circumference 

 of the animal is meant]. The acontia are very long, 

 pure-white bands, solely consisting of long cnida: ; 

 these latter being transparent cells, with more or 

 less prolonged, retractile [?] and bearded stylets, 

 called ecthorcea. These acontia are projected through 

 the holes (cinclides) of the integument, whenever the 

 animal is irritated, and serve as defensive organs. 

 The craspeda are similar bands of a yellowish 

 colour, but shorter, and never projected. These 

 appear to be connected with the digestive system : 

 their composition is similar to that of the acontia, 

 except that there is in the centre a considerable ac- 

 cumulation of an intercellular substance. The 

 ovaria are long strings, lying between the mesen- 

 terial folds : there are twelve pairs of them, com- 

 posed of eggs only. Thread-like organs, chiefly 

 composed of spermatozoa, appear to be only oc- 

 casionally formed. 



In this description the point of greatest novelty 

 is the presence of earthy scleroids of defined forms 

 in the column-wall. That such are found deposited 

 within the integuments of certain Echinodermata is 

 well known ; but this is the first time, so far as I 

 am aware, that they have been discovered in the 

 non-coralligenous Actinozoa. It is not impossible 

 that their presence may reward closer search in 

 some of our native species. 



Torquay. P. H. Gosse. 



Nothing useless is, or low ; 



Each thing in its place is best ; 

 And what seems but idle show, 



Strengthens and supports the rest. 



