THE CONCHOLOGIST, 



mitted down to generations witli cumulative 

 developments and adaptations from early 

 geological times to the present. We have 

 here a possible explanation of the presence 

 of a periostracum and shell to the mollusca. 

 It is, however, simply a suggestion borne out 

 in some measure by the developmental history 

 of the animal. 



(Geological evidence would also appear to 

 favour my views. Even in the earliest-known 

 Cambrian seas it would seem we are far 

 from the commencement of molluscan life, 

 and that they had undergone many changes 

 l)revious to this period. The complete 

 differentiation which the mollusca had already 

 attained at that time argues for a much 

 greater antiquity for them than this period. 

 Clenera and species of the LainelUbrauchiata 

 and Gastropoda do not occur until the 

 Tremadoc Slate beds, and it is noteworthy 

 they are few in number. Although no 

 doubt the obliteration by metamorphism 

 of organic remains has been excessive in the 

 beds older than the Tremadoc Slates, other 

 classes of animal life have been fairly well 

 l)reserved. Possibly the non-presence of 

 molluscan shells in these earlier beds is due 

 to their non-possession of a shell sufficiently 

 hard or solid enough to be preserved. 



^bc Concbolooist : 



A ()UARrKKLV Magazine for Cunchulogists. 



'■'The Co)iihologist" is publhlnd on cacli qiiaiicr-day. 

 Anintal Siihscriptioii, js. 6i/., post free. Single 

 Copies, lod. eaeli. 



All eoniinnnieations intended for puhlieation, advertise- 

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 preceding puhlieatioii, and addressed to 



W. E. COLLINGE, 108, U'oodsley Road, Leeds. 



March 25TH, 1891. 



The first number of T/ie CoiicJiologist a])pears 

 at the expressed wish of a nun^ber of con- 

 chologists, who require a medium for the 

 interchange of thought and the promotion of 

 their interests. It was originally our intention 

 to produce a similar paper to The Nautilus, 

 and if it received sufficient support, to issue 

 the same monthly. Our number of sub- 

 scribers having far exceeded what we antici- 

 pated, we have produced a much better 

 and larger paper ; and if the same support 

 is accorded to us at the year end, The 

 Condiologist for 1892 will be issued as 

 a bi-monthly. To those who have given 

 us their hearty support, and for their good 

 wishes, we desire to express our thanks. 



We are indebted to a number of our sup- 

 porters for various suggestions as to our 

 paper, some of which will be acted upon 

 in future numbers. We have the pleasing 

 duty of here acknowledging the receipt of 

 a number of ])hotographs from various con- 

 chologists, a list of which will appear in the 

 June number. 



