HARDWICKE'S SCIENCE-GOSSIP. 



269 



NOTES ON A CURIOUSLY DISTORTED 

 SPECIMEN OF HELIX NEMORALIS. 



I HAVE taken, during the past summer (1883), a 

 curiously distorted specimen of H. nemoralis 

 (plain pink variety). When I first observed the animal, 

 it was feeding on the coarse grass which covers the 

 sand dunes at Redcar. I noticed that the shell had 

 been slightly crushed on one of the upper whorls (I 

 have marked the locality by a black patch in fig. 167), 

 and also that the animal, having already completed 

 a normal lip, was commencing a farther addition to 

 his shell, and had then completed about one-sixth of 

 another whorl, which began just within the margin of 

 the lip. The new deposit of shell was, however, 

 colourless, very uneven, wrinkled, and exceedingly 

 brittle. I took the specimen home and placed it 

 among some of its fellows, in a vivarium which had 

 been stocked from the same locality some time pre- 

 viously. Although well supplied with food my little 

 prisoner seemed very inactive, though he continued to 

 add to his shell at intervals, and in the course of 

 about five weeks he completed quite half a whorl. 

 Having to leave home for a short time I was unable 



Fig. 167. — Distorted Specimen of Helix nemoralis. 



to watch him longer, and on my return I found him 

 in a dying state. After hot water treatment, I very 

 carefully extracted his remains, but only succeeded in 

 getting a portion of the dark -coloured part of his 

 anatomy which had occupied the upper whorls. I 

 however appeared to have taken out all that had 

 recently been alive. The extreme end of the dark 

 part was very large, and rather lighter in colour than 

 is usual, and when the animal was coiled, I saw that it 

 was not complete, though the skin was perfect. From 

 this I am led to believe that when the upper whorl 

 was crushed a part of the animal perished, and that 

 a process of reparation commencing, the animal found 

 himself growing too large for his abode, and endea- 

 voured to remedy the defect by the construction of 

 another whorL This is only surmise, and I should 

 be glad to have any collector's views on the subject. 



Fig. 167 shews the extra whorl, "A " being the first 

 lip ; " B " the second (incomplete for lack of ribs). 



The next figure gives another view of the shell, 

 exhibiting the second lip at " B," the first at " A." 



The last figure shews the inner margin of the_first 

 lip, in the region of the columella, within the aperture 

 " B." 



Middlesbrough. Baker Hudson. 



AN ANCIENT ATOLL REEF. 



IN the Geological Section of the British Association 

 Mr. James Thomson, F.G.S., of Glasgow, showed 

 that at Arbigland , fi fteen miles to the south of Dum fries, 

 the rocks along the shore for several miles consisted 

 of calciferous sandstone. In Arbigland bay the 

 lower members of the carboniferous limestone are 

 exposed in a series of sinuous bands of more or less 

 impure limestone. The limestone is largely composed 

 of corals of various kinds. The most abundant form 

 is Monticulopora. Indeed, in some parts this genus 

 forms the greater part of the limestone. There are 

 also masses of Lilhostrotion Martini, Diphyphyllum 

 fasciculatum, Syringopora, Cladochonus, Aulopora, 

 &c. This band of limestone extends along the shore 

 for at least two miles, and in Arbigland bay it forms 

 a deep semicircular ridge, recurring at either ex- 

 tremity, and extending along the coast line. Around 

 the inner margin of this ridge the limestone passes 

 into a dark calcareous, arenaceous shale, which when 

 split reveals numerous impressions of fucoids ; indeed, 

 the fucoids are so abundant, that they have rendered 

 this band a blackish-gray colour. This band passes 

 into a dark calcareous shale, indicating 

 shallow- water or shore conditions. Im- 

 bedded in this shale are numerous domes of 

 corals of various dimensions, belonging to 

 _ the genus Lithostrotion, chiefly Lith. Fle- 

 ming!, Lith. Portlocki, and Lith. M'Coyi, 

 with here and there crushed examples of 

 simple corals, principally that of the genus 

 Caryophyllum. '1 he total width of this 

 outer band of limestone or reef of coral 

 rock is 2976 feet, dipping inwards downwards to 

 the centre at aa angle of 45 degrees. Around the 

 inner margin of this semicircular mass there are ten 

 successive reefs, and all dipping inwards and down- 

 wards ; at the lateral margin of the tenth reef it 

 becomes less open, and the circular aspect is nearly 

 complete. The open space is to the south. Each of 

 the succeeding reefs is composed of the remaining 

 corals, chiefly belonging to the genera referred to. 

 On the southern open space, and inside of the semi- 

 circular reef, and imbedded in the calcareous shale, 

 the domes of Lithostrotion are of gigantic proportions. 

 One dome measured eleven feet ten inches in dia- 

 meter. These domes diminish in size on the opposite 

 extremity of the circle. The smallest specimen pro- 

 cured was one inch in diameter. Here, therefore, 

 around the inner margin of this nearly circular reef, 

 are domes of corals varying from one inch up to eleven 

 feet ten inches in diameter. These are intermixed 

 with masses of Lithostrotion Phillipsi, and a species 

 of fossil sponge, which has been described by Mr. 

 Carter as Pulvulus Th&msoni. One specimen of this 

 sponge measured eleven inches long, by five inches 

 broad. Those of larger dimensions were found at 

 the open face of the semicircular reef, diminishing in 



