(No) 
PREFACE. 
“Mire Collection, from which the shells described in the 
following pages have been carefully selected, was made at 
Mazatlan, (lat. 23° N., long. 107° W.) during the years 1848-50, 
by a Belgian gentleman named Frederick Reigen.” The bulk 
of that portion of it quoted in the following pages‘as the ‘Liver- 
pool Collection,’ was purchased by Herbert Thomas, Esgq., of 
Bristol, and Mr. P. P. Carpenter. The latter gentleman 
“selected from it as many specimens as might be required 
(1) to illustrate the local-fauna of a known station at the 
mouth of the Gulf of California ; and (2) to exhibit the 
amount of variation, whether great or little, observed in com- 
paring together large numbers of individuals in the various 
species. The latter object appeared of no slight importance, 
especially for the sake of inland naturalists ; who have usually 
to depend on the very limited number of specimens which are 
generally to be seen both in publicand in private collections.” 
This series Mr. Carpenter presented to the British Museum, 
on the understanding that it should be kept separate and 
intact for the purposes above named, like the Cuban, South 
American, and other local collections: he undertaking, at the 
same time, to prepare a Descriptive Catalogue, which is here 
printed. The descriptions of the Bryozoa, occupying the first 
six pages, were kindly communicated by G. Busk, Esq., 
E.R? 8. .&e: 
“The collection consists of about 8873 specimens (2505 Bivalves, 
&e., and 6368 Univalves) mounted on 2530 glass tablets. The © 
number to the left refers to the species, that to the right to the 
tablet in the Catalogue. The minute specimens are fastened 
on strips of thin glass enclosed in test tubes. By this mode of 
arrangement, both sides of the object can be seen without 
disturbance.” 
“The measurements (unless otherwise expressed) are thus 
taken. In the bivalves; Jong. from the umbo to the middle 
of the ventral margin ; /at. from the anterior to the posterior 
ends; alt. the thickness of the closed valves. In the spiral 
univalyes ; dong. from the vertex to the base; long. spir. from 
