HARDWICKE'S SCIENCE-GOSSIP. 



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grew together into a cluster, but so grew as to form a 

 single cup, nearly four inches in diameter, not unlike 

 a shallow convolvulus with a very irregular margin. 

 The cup so formed, however, was not complete, 

 having a slit down one side — a feature I should per- 

 haps not have noticed had not the figure in Dr. 

 Masters's work shown the same formation very 

 plainly, whence I infer that it may be usual. Inside 

 the cup was only a confused mass of distorted petals, 

 stamens, or carpels, while below it was an involucre 

 formed by the cohesion of the bracts of the several 

 flowers. When I gathered the specimen last June, 

 every other stalk on the plant showed promise of 

 producing a similar irregularity, though then only in 

 bud. — John W. Buck, B.Sc, New Kingswood School. 



Destruction of Isoetes lacustris by Fish. — 

 I was geologising lately at the lakelets on the ice- 

 worn summit of Fairhead, county Antrim, and ob- 

 served a large quantity of fragments of the quill-like 

 leaves of Isoetes lacustris floating in the water. On ex- 

 amining the pieces I found they were all freshly 

 champed and bitten, the broad, flattened part of the 

 base was in every instance almost eaten away. Turn- 

 ing into a shallow little bay, I found this wholesale 

 destruction of this very interesting plant was caused 

 by a number of common black trou-t. They were 

 busily engaged nibbling and biting off the basal part 

 of the quills. I saw several of them with portions in 

 their mouths darting away into the deeper water. The 

 weather was very dry, and had been so for a long 

 time previous ; in consequence, the water of the 

 lakelets was low, and the brooklets flowing into them 

 were all dried up. The supply of worms and other 

 food brought down into the lakelets by the streams 

 was cut off owing to this cause, and the fish were 

 forced to feed on the Quillwort. This was the only 

 plausible explanation I could offer to account for the 

 strange conduct of the fish, but perhaps some of the 

 readers of Science-Gossip have observed something 

 similar, if so, [ would very much like to be informed 

 of the circumstance. In conclusion, I may state that 

 the Quillwort, Isoetes lacustris, is a very rare and local 

 plant in this district ; only two stations are recorded 

 for it in county Antrim, these are the little lakelets on 

 Fairhead, and the river Bann, near Jackson Hall. — 

 William Gault, Belfast. 



GEOLOGY. 



Dwarf Fossil Crocodiles. — Professor Owen has 

 recently described some fossil crocodiles found in 

 rocks of Purbeck age, under the name of Theriosuchus 

 pusillus. This crocodile was only 18 inches in length. 

 As regards its derivation, it appears to be related to 

 the theriodonts of the Trias. 



The Upper Greensand Coral Fauna of 

 Haldon, Devonshire. — This was the title of a 

 paper recently read before the Geological Society, by 



Professor P. Martin Duncan, F.R. S. The author in this 

 paper stated that since the publication of his supple- 

 ment to the " British Fossil Corals," published by 

 the Palaeontographical Society, several new corals 

 have been obtained at Haldon by Mr. Vicary, of 

 Exeter. Twelve additional species were noticed, of 

 which ten were new. This brings the total number 

 of species in the Haldon greensand up to twenty-one. 

 The new species are thus distributed : — Aporosa : 

 Oculinidse (1), Astraeidae (3), Fungidoe (5) ; Per- 

 forata: Turbinaria; (2); Tabulata (1). The paper 

 concluded with remarks on the genera and species 

 represented, from which it appeared that the coral 

 fauna of Haldon is the northern expression of that of 

 the French and Central European deposits, which are 

 the equivalents of the British upper greensand. The 

 Haldon deposit was formed in shallow water, and the 

 corals grew upon the rolled debris. 



Holes in Oolitic Limestone. — In Science 

 Gossip for November, F. N. D. asks why holes are 

 found in oolite beneath sand. I cannot say for certain 

 that the cause I have seen at work with a similar effect 

 is certainly the cause for the holes mentioned ; but as I 

 know of no other equally efficacious, I tell him what 

 I have seen. Holes in limestone and basaltic rock 

 caused by small surface hollows — water percolating 

 through the superstructure acts on sand particles in 

 these hollow places, and the sand grains act as 

 gimblets or gouges by constant friction ; the rock is 

 worn away, and holes are made for a few inches to 

 many feet in diameter. In the large holes pebbles 

 and gravel take the place of sand, and wear out deep 

 cavities ; in places where the water action is confined 

 to dripping, the holes are deep and uniform ; where 

 they are exposed to running water the erosion assumes 

 varied shapes. The holes described by F. N. D. are 

 most likely made by water drops and sand in a rock 

 formed of some shale or soft material. — H. P. M. 



The Thermal Sources of Carlsbad. — The 

 recent demolition of a house has led to the discovery 

 of a remarkable geological fact — the existence of 

 a peculiar zone, about 15 to 20 metres broad, be- 

 tween the steep pyritose granite, with frequent veins 

 of hornstone on which the town tower stands, and the 

 similarly pyritiferous granite creeping out beneath the 

 terrace of the Schlossberg. This zone is filled up 

 with a breccia of granite and hornstone, with thermal 

 waters circulating everywhere within its fissures, and 

 depositing on their inner surfaces crusts and veinules 

 of arragonite, some of them \\ metre thick. The 

 temperature of the whole zone is high, on account of 

 the warm water and steam issuing out of every cleft 

 and crevice. 



Marine Fossils in Gannister Beds.— I was 

 much surprised to learn that Professor G. A. Lebour 

 announced the discovery of marine fossils in the lower 

 coal measures or "gannister beds" of Northumber- 

 land, and that "hitherto no marine fossils had been 



