HARDWICKE' S SCIENCE-GOSSIP. 



23 



Dreissena polymorpha. — Whilst paddling up 

 the Thames in search of microscopic material I came 

 to a low weir whose well water-worn and green and 

 brown timbers seemed to promise good hunting ground. 

 On looking down into the water I saw attached 

 to the stones and in the interstices of the wood-work 

 masses of shells attached by their byssi that looked 

 exactly like the common marine mussel [Mytilns 

 ednlis). A close examination and dissection how- 

 ever proved it to be Dreissena polymorpha, a native 

 of the Black Sea, the Danube and the rivers of 

 Russia. In Turton's " British Shells " it is mentioned 

 as occurring in the Commercial Docks, the Union 

 Canal and the river Nen in Scotland where it has 

 been probably introduced, adhering to Baltic timber, 

 and it is highly probable that it was introduced by 

 the same means into the locality where I found it, 

 /.»•., on the timber used in constructing the weir. 

 It is at once distinguished from the common Thames 

 swan mussel {Anodon cygneits) by its shape and I 

 byssus, and from the marine mussel by its mantle ! 

 being continuous, except just where the two siphons 

 protrude, and by the shell possessing a septum. It 

 is said to be capable of living out of the water for 

 several weeks, and although I have not tried the 

 experiment I have some in a glass jar filled with 

 water that seems none the worse for the confined 

 space and absence of the running water that I found 

 them in. The shell is a dark brownish-olive, equi- 

 valve, deeply keeled and inequilateral. The beaks 

 very acute, and bent down a little, they almost touch, 

 and are furnished internally with a septum. The 

 interior is milky-white, indistinctly iridescent. The 

 animal has the mantle closed all round, except small 

 openings for the foot and the two siphons. The 

 mantle is of a creamy-white colour, and towards the 

 wider basal portion it becomes of an orange colour 

 bordered with two blackish or deep purple borders. 

 The foot is pale yellow, with a tuft of byssus at the 

 base and a distinct byssal groove. I shall be very 

 pleased to point out the locality where they occur, or 

 to forward specimens to any one interested in British 

 freshwater conctiology. — E. Gardner, Shepperton. 



Late Swallows. — Horace Pearse, F.L.S., Stour- 

 bridge, says he saw a swallow on the 5th of November. 

 I have in print a statement that I saw a chim- 

 ney swallow on November 13th, 1875, about noon, 

 flying before my windows in my garden ; about two 

 hours afterwards I saw one, but whether it was the 

 same I do not know. Swifts, chimney swallows, 

 swallows or house martins, and the sand martin. The 

 Swift comes late and goes early. Swallows, the 

 woodcock, snipe, cuckoo, nightingale, wryneck, and 

 many others. The locality has much to do with their 

 appearance, for the place where they leave the coast 

 must be the last place where they are seen, and the 

 place on their return where they first reach land must 

 be the first before they disperse themselves over the 

 countr)'. — Thomas Kingsford, Canterbury. 



An International Association for the obser- 

 vation OF Hailstorms. — Mr. J. A. Westwood 

 Oliver has notified to us his intention of endeavour- 

 infT to organise an International Association for the 

 observation of Hailstorms, and wishes any of our 

 readers who are interested in Meteorology, to com- 

 municate with him at the London Institution, Fihs- 

 bury-circus, E.C. Mr. Westwood Oliver states that 

 no other instruments than an ordinary barometer and 

 thermometer are needed. 



Correction. — Through an oversight, fig. 141, 

 p. 244 (last vol.), represents a rhombic, instead of a 

 pentagonal dodecahedron. — E. H. 



NOTICES TO CORRESPONDENTS. 



To Correspondents and Exchangers. — As we now 

 publish Science-Gossip earlier than heretofore, we cannot 

 possibly insert in the following number any communications 

 which reach us later than the 8th of the previous month. 



To Anonymous Querists.— We receive so many queries 

 which do not bear the writers' names that we are forced to 

 adhere to our rule of not noticing them. 



To Dealers and others. — We are always glad to treat 

 dealers in natural history objects on the same fair and general 

 ground as amateurs, in so far as the " exchanges " offered are fair 

 exchanges. But it is evident that, when their offers are simply 

 disguised advertisements, for the purpose of evading the cost of 

 advertising, an advantage is taken oi a\ix gratuitous insertion of 

 "exchanges" which cannot be tolerated. 



A. W. Preston. — We do not undertake to return specimens 

 sent us to be named. 



" MucROSS." — The specimens are fungi, the yellow one being 

 Tremella tnesenterica, and the white Tremella albida. 



T. B.— Get the " Pocket Guide to British Ferns," by M. S. 

 Ridley, price is. dd., published by D. Bogue. It will give you 

 just the information you seek. 



P. Barker. — A general index of the first 12 vols, of Science- 

 Gossip was published at the end of 1876, price is. 6d., and may 

 be had of our publisher. 



Grantlev. — Your clams are a species o( Cyikerea, not found 

 in British seas ; but there is no reason in the world why they 

 should not be acclimatised as food animals in our waters. 



J. B. M. — The "Aquarium" gives a list and description 

 of fresh-water animals suited to an aquarium. Spence Bate's 

 work on the sessile-eyed Crustacea includes those you mention,, 

 but it is rather expensive. 



J. B. J.— Rimmer's " Land and Freshwater Shells " is by far 

 the best for your purpose, as it contains a photograph of every 

 species. Price io,f. dd., published by D. Bogue, 3 St. Martin's 

 Place, Trafalgar Square, W.C. 



Elliot. — The bones of Ichthyosaurus and Plesiosaurus are 

 very frequently found in the boulder clays of Norfolk and 

 Suffolk. They have been deposited therefrom the wreck of the 

 oolitic rocks. 



J. T. Hillier. — Your specimen is the bird's nest (Nidularia), 

 and the shell a species of Pisidium. 



R. B.— Professor Greene's " Physical Geology" is by far the 

 best we know for bringing up all matters to_ the most recent 

 date. 



T. L. — Any of the microscope makers advertising in our 

 columns will answer your query more satisfactorily than we can. 



J. W. O. — It is very difficult to safelj' name the species of 

 corals from such small fragments as those sent, as much 

 depends upon the manner of branching. But we have little 

 doubt as to the genera, which are as follows : i, Fungia, 2, 

 Creusia, 3, Pocillipora, 4 & 5. Stylaster. All are concerned in 

 reef- building, but especially the last four, which are now classed 

 as Hydrozoan corals. 



F. H. S — We are not aware that the common centipede 

 when crushed gives outa phosphorescent light, but the common 

 millipede [Geophilus electricns] constantly leaves a phospho- 

 rescent trail. The insect you enclosed is the common cricket 

 (Ache t a dornestica). 



F. H. Hele. — We have never seen or heard of scarlet fluor- 

 spar ; Saxony and Alston Moor produce rose-coloured cubes, 

 and nearly orange-coloured crystals are obtainable in Derby- 

 shire, the colour being due to iron oxide. 



J. W. W. — You will find in " Notes on Collecting and 

 Preserving Natural History Specimens," published in 1875, 

 price 3J. td., edited by the Editor of Science-Gossip, that all 

 the subjects you mention have already been treated upon, from, 

 geology to entomology, and that each subject was written 

 upon by well-known writers in each department. 



V. G. — Your tree (as indicated by the fruit sent) is the Wild. 

 Service Tree {Pyrus torinhialis], 



T. B. W. — The plants are, i. Anemone sulphurea, and 2, Bi- 

 scutella lavigata (Cruciferae). 



TEXCHANGES. 



Side-blown eggs of golden-winged woodpecker offered ; 

 desiderata, eggs (side-blown), merlin, hobby, wood-sand- 

 piper, Brummich's guillemot, bridled guillemot, gull-billed 

 tern, white-winged black tern, great black-backed gull, &c. 

 Offers solicited. — W. Wells Bladen, Stone, Staffordshire. 



