196 SOME MINOR PROBLKMS CONCERNED IN THE LCCAL 



list which have passed, or are passing away, we can assign absolutely 

 no rea50n, nor does it seem that we are on the road to a solution ; 

 their food even, for the most part, is not known. 



Some forms, on the other hand, now living in fair numbers, but 

 not represented in the marl, seem to claim to be regarded as new 

 introductions. It is true that negative evidence is always suspicious, 

 but it is also true that the marls have been well examined. There is 

 no reason that we know for the preservation of one shell more than 

 another ; therefore, if they had lived on the spot, we might reasonably 

 suppose that their remains would have been found. The largest of 

 these apparently new introductions is Helix virgata. In my own 

 parish (Felstead) it is rare. In an adjoining parish (Stebbing) it is in 

 one part very common, occurring literally by thousands. It is 

 quoted by Mr. Crouch (E. N., vol. iv., page 210) as occurring near 

 Barking Creek. It is also included in Dr. Laver's list. (Trans. 

 E. E. C., vol. ii., p. 95). Its absence from the marls is very striking, 

 as it is a conspicuous shell, and gives us every rtason for believing 

 it to be a new arrival. 



I may here add -that 1 am continually expecting the arrival of 

 four other large forms which, on the same reasoning, have never 

 before visited this neighbourhood. They are the two Falitdiuas, 

 Unio iumidtis, and Planorbis conieus. The first is common in South 

 Essex and surrounding counties, the second in many parts of Essex 

 and surroundings, and the last, long a resident in South Essex, 

 occurring fossil in the Thames alluvium, has now reached Chelms- 

 ford, as we have seen. 



Our local list of reptiles furnishes but little from our present 

 point of view. The case of the Common Ringed Snake and the 

 Adder demands a passing notice. From what information I can 

 obtain, which is confessedly fragmentary, they both appear to be 

 dying out in a tract of land say ten miles wide, beginning at 

 Danbury Common and extending northwards as far as the river 

 Stour. Thus, in the Sampfords and Bardfields, both species appear 

 to be extinct. At Finchingfield and Wethersfield and Stebbing, 

 snakes are very rare and adders are unknown. In the neighbourhood 

 of Felstead both have markedly diminished within the last forty 

 years, whilst at Danbury Common both species still survive in 

 numbers, although the snakes are much in excess of the adders. I 

 have taken much trouble to obtain information as to my own neigh- 

 bourhood, and believe I am correct in saying that the adder is now 



