J 34 



HA RD WI CKE 'S S CIENCE- G OS SI P. 



THE GREAT INTERNATIONAL FISHERIES 

 EXHIBITION. 



ALL lovers of the angle, and those who are 

 interested in any of the numerous ways in 

 which pisciculture affects us, should visit the above 

 Exhibition, which doubtless will remain open during 

 the summer months. English people are interested 

 in everything relating to the sea. This is proved by 

 the fact that on Whit-Monday no fewer than 44,000 

 people passed through the Exhibition. The number 

 of objects brought together from every civilised 

 country in the world is truly marvellous, and although 

 the greater part of them very naturally relate to the 

 economic side of Ichthyology, &c, there still remain 

 large numbers to interest the pure naturalist. The 

 official catalogue extends to nearly 600 pages and 

 is admirably drawn up. It contains short, practical 

 essays by well-known writers on matters relating to 

 fish and fishing. As might be expected, the United 

 States and Canada are very strongly represented in 

 the exhibits ; next to them come Norway, Sweden, 

 and Holland. The objects gathered together in these 

 courts alone would make a magnificent exhibition. 

 Fish-hatching is shown by several contrivances ; 

 oyster breeding, lobster breeding, &c, are also illus- 

 trated on an extensive scale. There is a superb col- 

 lection of stuffed fish sent by various angling societies 

 and celebrated anglers, representing, as might be ex- 

 pected, the largest specimens of each kind of fresh- 

 water fish. Perhaps there is a trifle too much pike 

 about ! Some of the coloured casts of fishes are 

 exceedingly well done. The models sent by Mr. 

 Searle of diseased salmon are of great interest ; Mr. 

 Rae, of Coventry, shows the microscopic parasites 

 which affect fish ; Mr. T. Bolton, of Birmingham, has 

 a stand where various living microscopic and other 

 organisms are exhibited ; Mr. Edward Lovett exhibits 

 exquisitely mounted slides, illustrating the embryology 

 of Crustacea ; Mr. Brotherston, of Kelso, shows 

 mounted specimens of freshwater plants ; Mr. Bryce 

 Wright has a splendid series of corals, sponges, mol- 

 lusca, &c; Dr. Dohrn sends specimens of Entozoaand 

 Epizoa affecting fishes ; and Dr. Spencer Cobbold has 

 a collection of no fewer than 80 species of fish para- 

 sites. Other objects of high interest to the naturalist 

 are Professor Sars' illustrations showing the embryolo- 

 gical development of the codfish ; Professor Traquair's 

 exquisite illustrations in pencil of British fossil 

 fishes ; Mr. Cholmondely Pennell's pictures of fishes ; 

 and Professor Mackintosh's series of original coloured 

 drawings of annelids. 



We would also draw attention to Mr. J. Eede's 

 collection of insects injurious to fish and those on 

 which fish prey ; and especially to Mr. J. T. Car- 

 rington's preserved specimens of Crustacea. There is 

 a large series of British aquatic birds, and of birds 

 whose natural history in any way brings them into 

 relationship with fishes. As the natural history 



department of the exhibition is of a competitive 

 character, there is necessarily a great deal of repeti- 

 tion in the objects. This, however, need not be a 

 drawback, and we would direct attention to such 

 incidents as the markings and mottlings on the 

 common pike. These usually range from bars to 

 spots, and may be related to the character and 

 depth of the water they inhabit, &c. The natural 

 history student who is weary of the crowds of 

 objects which meet his eyes in the courts and 

 galleries may either amuse himself by observing the 

 living objects in the large and extensive aquarium, 

 or, still better, by strolling into the pleasant grounds 

 and watching the live flamingoes, pelicans, and 

 other aquatic birds in the artificial waters. 



THE CONTROVERSY ON THE ARCHEAN 

 ROCKS. 



PROFESSOR GEIKIE'S challenge as to the 

 genuineness of the so-called Pre-Cambrian or 

 Archean rocks, contained in his paper read before 

 the Geological Society (an abstract of which was 

 published in the last number of Science-Gossip), 

 has caused quite a keen controversy. The second 

 part of the paper was read on April nth, when a 

 sharp discussion followed. In the second part of his 

 paper, Professor Geikie gave the results of the survey 

 which he had made of the district with Messrs. Peach 

 and Topley, and of his study of a series of more than 

 100 thin slices of the rocks collected at St. David's. 

 He found that he could corroborate generally the 

 descriptions of previous writers on the microscopic 

 structure of the rocks, and that investigation with 

 the microscope amply confirmed the deductions he 

 had drawn from observations in the field. 



I. Order of Succession of the Rocks. — The following 

 rock-groups in the Lower Cambrian series are recog- 

 nisable at St. David's, and are given in descending 

 order : — 



4. Purple and greenish grits, sandstones, and 

 shales. 



3. Green and red shales and sandstones, with 

 true tuffs {Lingulella primccva). 



2. Quartz conglomerate. 



1. Volcanic group (tuffs, schists, lavas). 

 The volcanic group forms the oldest part of the 

 Cambrian series at this locality. The bottom is not 

 reached ; but about 1800 feet are visible. It consists 

 mainly of purplish-red, green, grey, and pale tuffs, 

 with occasional breccias and bands of olivine-diabase. 

 Analyses of some of these rocks had been made by 

 M. Renard, of Brussels. The tuffs are partly basic, 

 derived from the disruption of diabase lavas (48 per 

 cent, of silica), partly acid, from the destruction of 

 fine felsites (72-80 per cent, of silica). The micro- 

 scopic structure of the tuffs was described, and slides 

 and drawings were exhibited. The lavas are varieties 



