THE - CONCHOLOGISTS’ - EXCHANGE. 117 
in exchange should be determined by 
Bhe Srcehctonists cine: | their rarity, condition and history. 
Should a shell be rare it cannot be rea- 
A Publication designed for Conchologists and | sonably expected for a common one. A 
Scientists generally. 
ISSUED MONTHLY 
BY 
WM. D. AVERELL, 
Epitor AND PuBLisHER 
8a Correspondence upon Conchology, as well as 
reliable items of interest concerning the Mollusca, 
their habits, localities, ete., kindly solicited from all. 
Matter for publication must be received by the 
tenth of each month. 
Draw Money Orders upon Station H, Philadel- | 
phia, Pa. 
SUBSCRIPTIONS. 
One year, post-paid.......... 
Three months, us 
Six fe 
To Foreign Countries.. ... -ocece 
To countries not in Universal Postal Union. pee qiay 2 
SinpleycOplesscaccercecsseccsesvecceccnenenscnemaewenttacescacs Gye 
ADVERTISING RATES. 
Vapi Cliteesscndesececocovees 20) | La Chiseeeesecerernsnscesse $ .50 
1 4nch, 3 months....... 1.00 | 44 column, 1 month, 2.00 
¥% column, 3 months, 4.00] 1 “column, 1 month, 4.00 
1 column, 3 months.. 8.00 | 1 column, 6 months, 12.00 
Entered at the Post-office at Philadelphia, Pa., as 
second-class matter. 
SUBSCRIPTIONS TO VOLUME II ARE NOW 
DUE. FOR EXPIRATION OF SUBSCRIPTION SEE 
DATE ON WRAPPER. 
Editorial Zlotes. 
SEVERAL communications have been re- 
ceived asking us for our opinion upon what we 
shall term the Standard of Exchange. What 
shells to exchange, and how to exchange them 
to the best advantage, must be determined by 
the owners, while the number and quality of 
specimens to be sent must be regulated by the 
| genera, such as Mya, 
number and quality of specimens to be received; 
that is self-evident. The relative value of shells 
Scalaria pretiosa would not be traded evenly, 
by a well-informed collector, for a Purpura 
hemostoma, simply because, as values run, shells 
such as these are greatly different i in price. And 
so with all shells, concessions should be made 
and extra specimens sent by the collector offer- 
ing ordinary shells for rarer ones. A reliable 
price list will be of great aid in adjusting ex- 
changes. Condition is also a very important 
preliminary to atrade, as no one wants poor 
shells, and everybody wants good ones. There 
are occasions, however, when a poor shell is 
| far more valuable than a good one, simply be- 
cause of its rarity and value for study. In the 
case of rare bivalves a single valve is accepta- 
ble to many collectors who value true science 
above mere show and who prefer half a shell 
to none at all. Therefore, condition, while 
exceedingly important in exchanging, must de- 
pend upon rarity in many cases ; ‘while in a 
moral sense, and everything else being equal, 
it is both wise and safe to treat your corres- 
pondents liberally, and to send them as good 
shells as theysend you. So far as possible 
shells sent in trade should have the epidermis, 
and should be free from borings, cracks and 
scratches. Bivalves should be matched, with 
hinge entire, and when belonging to the gaping 
Pholas, Petricola, etc., 
should have as much of the mantle preserved 
as possible; teeth perfect, and umbones, unless 
naturally eroded, entire. Univalves should 
have the spire intact unless zaturally decollated 
as in many Melanias, Viviparas, etc.; the 
operculum should be provided where possible; 
and in all cases the body-whorl should be en- 
tire and wot filed. Wy the history of a shell 
we mean its name and location and other data 
which is ordinarily } laced upon a label. Col- 
lectors offering shells with complete and accur- 
ate histories can com:nand better trades than 
those having the material without that ad- 
vantage. In these days of hurry we all want 
to save as much time as possible and readily 
recognize the importance of trading with those 
having desirable shells, in good condition, and 
provided with reliable histories. 
