32.— Unio pressus, Lea. 
An inhabitant of Pope and Edwards Creeks 
where it is found very rarely. It seems to have 
habits very similar to Unio spatulatus, being 
found in localities where iron ore is abundant, 
and is found buried in piles of loose stone and 
gravel. As found here it is always beautifully 
rayed. 
33-— Unio rectus, Lam. 
This fine species inhabits the deep water of 
the Mississippi and is seldom found near the 
margin. It is a smooth, wide species and in 
many respects resembles gzdéosus, but it is very 
distinct from that species as the undulations 
on its beaks are not so coarsely granular, it has 
a smoother epidermis, it; is more beautifully 
rayed and is generally much straighter on both 
its dorsal and ventral margins. The male 
differs greatly from the female in outline. 
Some specimens have a pink nacre, others are 
white inside, while most of those found here 
are of a pale pink color in the beak cavity 
gradually fading to a pale rose color towards 
the anterior and posterior portions of the shell. 
The species often attains an immense size and 
is found in the Mississippi River and all 
streams emptying into it, from Minnesota to 
Arkansas. 
To be continued. 
PLANORBIS DILATATUS, GOULD, 
IN ENGLAND. 
BY THOMAS ROGERS, MANCHESTER, ENGLAND. 
During the Summer of 1869,1 found a 
Planorbis in one of the canals near Man- 
chester which, after some investigation, was 
determined by Dr Gwyn Jeffreys as the P/an- 
orbis dilatatus,” Gould. Shortly after this 
discovery I found it again in another canal on 
the opposite side of the city, some five miles 
apart. The conditions under which it was 
found were similar in every respect, viz: near 
a cotton mill, where the refuse from the blow- 
ing room (cotton cleaning), was blown over 
and about the canal and where, in close con- 
tiguity, the warm water from the condensing 
THE - CONCHOLOGISTS’ - EXCHANGE 63 
engines ran into the canal and raised the tem- 
perature of the water a great many degrees 
higher than the other parts of the canal. From 
the foregoing facts Dr.Jefireys and 1 concluded 
that the species had been introduced from 
America with the cotton used at some period 
by the mills. And I further surmised that the 
introduction had been made during the English 
| cotton famine brought about by the war be- 
| tween the North and the South when cotton 
played a considerable part in the transactions 
of that severe struggle and when Lancashire 
people were glad to get it in any condition, 
wet or dry, blockade-run or otherwise. 
Coming to this conclusion in reference to its 
introduction in England, Dr. Jeffreys wrote 
about that time to Mr. John G, Anthony, the 
eminent American conchologist, who said that 
he did not think that Plaenorbis dilatatus,Gould, 
occurred in any of the cotton growing states, 
and that in his opinion it was essentially a cold 
water species. He also said that the species 
had been described from specimens collected 
in a pond near Cincinnati, Ohio, and named 
by Mr. Lea as P. /ems, but as that name was 
subsequently found pre-occupied by a fossil 
species, it was named by Dr. Gould as Plan- 
orbis diatatus. In a subsequent letter to Dr. 
Jeffreys, dated December, 1869, Mr Anthony 
said that he had written to Mr. Lea and other 
_ conchologists for further information as to 
| localities where it was found. 
During the year 1871, Dr. Jeffreys paid a 
_ visit to America and brought home to England 
two specimens of the P/axorbis, one of which 
he sent tome. This lack of specimens which 
he brought, and their absence from the col- 
lections of American shells in England, have 
led me to suppose that the species is some- 
what rare in the United States, and it has 
occurred to me that some further information 
might be acquired through the pages of your 
excellent ‘‘Conchologists’ Exchange”’ and that 
it might be interesting to your American 
readers to find out or record the distribution 
of this species, its habitats and its relative 
scarcity or abundance, and whether it would 
be likely to have attached itself to submerged 
cotton when used for defensive purposes during 
| the war before mentioned. 
