* 
e ob NBSS 1) 
e . 
XVIII. A Synopsis of the Testaceous Pneumonobranchous Mol- e 
lusca of Great Britain. By J. G, Jeffreys, Esq. Ina Letter — 
addressed to L. W. Dillwyn, Esq. F.R. and L.S. E M 
Read November 18, and December 16, 1828. 
Dear Sin, - 
Ir you think that the following account of an interesting branch 
of our native Testacea, | compiled from my own observations and 
a careful investigation of those authors who have written on the — 
subject, will be found worthy the notice of the Linnean Society, | 
I shall be glad to avail myself, with permission, of your medium 
in submitting it to that learned body. The few changes i in sy- 
stem and nomenclature which I have ventured to propose are 
very partial, and I am sure that you will think with me that they 
are justifiable i in an attempt to ascertain uncertain characters, or 
determine new ones. Ido notlay much stress upon the distinct- 
ive marks furnished by the animals of this order specifically con- 
sidered, though I am fully aware of their importance in forming 
the leading features of the higher divisions. The accompanying 
catalogue will I believes) be found to gee all iv species 
