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HARDWICKE'S SCIENCE-GOSSIP. 



size to an inch inside of the circle, where the water 

 was less pure, and where consequently the conditions 

 were less favourable. These facts imply conditions 

 similar to those described by Dana and Darwin in 

 the seas of the present day. The shale passes into a 

 calcareous sandstone, in which are found numerous 

 fossil shells, chiefly a small variety of Productus 

 gigantcus. The sandstone deposits are overlaid by a 

 bed of limestone three feet thick, largely composed of 

 fossil corals of various kinds. Monticulopora is largely 

 represented, together with masses of Lithostrotions, 

 chiefly Lith. junceum, Lith. Phillipsi, Syringopora, 

 Aulopora, and Cladochonus, &c. This reef is circular 

 in outline, and the limestone becomes more arenaceous, 

 and then passes into a calcareous shale. Here again 

 there are domes of Lithostrotion, but of greatly 

 smaller proportions, surrounded with indications of 

 shallow water during their life. This circle is 240 feet 

 in diameter, inside of which there is a succession of 

 fringing coral reefs, but all indicate that the con- 

 ditions were less favourable for their growth, than are 

 found in the outer and larger reefs, and which pass 

 into a band of calcareous sandstone seven inches 

 thick, which forms the floor of the centre of the 

 circle. The total facts indicate that the old coast 

 line was fringed first by a series of linear reefs, which 

 became more and more circular until in the centre of 

 Arbigland bay they assumed a circular form. Mr. 

 Thomson gave his reasons for supposing that the 

 water in the centre, when the outer reef was young, 

 was at least upwards of fifty fathoms deep. The 

 shale, or hardened calcareous clay, is largely composed 

 of triturated coral rock, was silted in from the open 

 sea by the opening in the south side of the reef. The 

 silt inside the circular reefs was washed inward 

 between the masses of coral. The domes and simple 

 corals imbedded in the mud, just as we find in 

 Atolls of present seas, plainly point to similar con- 

 ditions to that now existing. The Atoll at Arbigland 

 is the first one recorded of carboniferous age. 



A DAY'S MOSS-HUNTING AT THE 

 LAND'S END. 



SOME years ago, in the course of conversation 

 upon the relative productiveness of the 

 different counties of England from a bryological point 

 of view, a question arose as to the probable number 

 of mosses which might be collected in the course of 

 a few walks from any one spot in a tolerably good 

 district ; and I remember that the estimates were 

 widely diverse ; although very likely each would 

 have proved sufficiently near the mark if distinct 

 localities had been specified and actually put to the 

 test. Every one knows that certain districts in 

 England are, from some cause which is not always 

 apparent, vastly richer in variety both botanically 

 and entomologically than others possessing somewhat 

 similar features, and yet the unexpected discoveries 



which are continually being made and the unlooked 

 for things which year after year turn up and reward 

 the persevering naturalist, all tend to confirm and 

 strengthen the common saying which has now almost 

 passed into a proverb : " The best- worked district 

 produces most." 



As regards cryptogamic plants, the Land's End, 

 judging by the lists published in the Transactions of 

 its local society, can hold its own against many 

 favoured localities in England, and in the matter of 

 mosses it may take at least a respectable position. 



Early in September I planned a fair day's walk, 

 having for its object merely the cataloguing of all 

 mosses which should come under my notice ; simply 

 indeed to satisfy my own curiosity, and the result 

 having somewhat surpassedmy expectations, I purpose 

 giving, as concisely as I can, an account of my findings, 

 in the hope that it may not be altogether without 

 interest to those readers of Science-Gossip who 

 happen to be bryologists. By the way, the word 

 Bryologist is very uncouth and ponderous for common 

 use, and Muscologist is a hybrid barbarism ; cannot 

 some more simple term be brought into use, say 

 Mossists, a compact designation which at once 

 explains itself ? 



A couple of miles from Penzance there is a tolerably 

 large bog, known as Tremethick Moor ; it is rich in 

 plants, some of which, like Hypericum Bceticum and 

 Pinguiada grandijlora, are noted rarities. The 

 latter was introduced from Ireland many years ago, 

 and is now well established and thriving. This bog 

 I considered a good starting-point, for although I 

 determined that this should be a bona-fide single 

 walk, there could be no reasonable objection against 

 selecting such a one as would afford the best variety 

 of hunting-ground. 



On the way to Tremethick Moor a few species 

 caught my eye, and they served to head the list ; viz., 

 Tortula liivipila and Zygodon viridissimus on trunks 

 of trees, and Atrichum tindulatum, Hypmim 

 confertum, Weissia controversa, and Pogonatum 

 nanum, on the stone hedges by the roadside. No 

 better field could be found than this bog for studying 

 the infinite variation of the sphagnums ; many species 

 and no end of varieties and forms grow side by side, 

 or even intermingled in the same clump. Here are 

 Sphagnum acutifolium, with its legion of variations ; 

 S. subsccundum, var. rufescens, S. papillosum, some 

 bright-coloured tufts of S. rubcllum, with the clavate 

 male amentula of a deep rich purple, and large 

 cushions of S. intermedium, which is without excep- 

 tion the most beautiful in habit and colour of all our 

 sphagnums, especially when it grows to a height of 

 ten inches or so. Intermixed with sphagnum, almost 

 everywhere I observed Aulacomnion palustre and 

 Dicranum palustre, and in some of the wettest parts, 

 fringing the little watery hollows so rich in desmids 

 and other algoe, Hypnum revolvens, H. intermedium, 

 H. stellatum, H. aduncum, H. sarmentosum, and 



