xii INTRODUCTION. 
I may avail myself, however, of this occasion to state why I believe that Professor 
M’Coy was the original discoverer of the peculiar muscular action on a leverage supplied 
by what he calls the “entering valve,” which, in the absence of the cartilage, enabled 
the Brachiopoda to open their shells “in a manner unexampled in Lamellibranch Bivalves” 
(infra, p. 191). 
Sometime after the return of Mr Jukes to England, he presented several excellent speci- 
mens of an Australian Terebratula to our Museum. I cannot fix the date of their arrival; but 
it cannot have been later than 1848, or the early part of 1849. Very soon afterwards Professor 
M*Coy carefully examined these specimens, and found in some of them the animal structure so 
entire, and so well connected with the shell, as to demonstrate the true function of the 
peculiar muscular apparatus alluded to above. He pointed this out to myself, and afterwards 
to others (among whom I may mention Mr Hopkins); and at the same time dwelt upon its 
importance as throwing a new light on the internal and hitherto almost inexplicable structure 
of the shells of many Brachiopoda. I urged him to publish this discovery; but he refused to 
do so, and stated that it should appear in his description of the Paleozoic Brachiopoda of 
the Cambridge Museum. He never made any secret of it; and, among others, exhibited it to 
Mr Morris (the author of the Catalogue of British Fossils), than whom there is not a 
Palzontologist in England more likely to have known of the discovery, had it been already 
made by any of his friends before his yisit to Cambridge. That visit was made long before the 
publication of Mr Woodward’s “Manual.” I cannot fix its date; but I believe that it took 
place some time during the year 1849. Mr Morris had not, then, seen any explanation of this 
peculiar mechanism within the shells of Brachiopoda, or heard of it; and he requested and 
obtained a drawing of it from Professor M‘Coy, which he took back with him to London. 
Along with this drawing was, if I mistake not, a description of some new species of Oolitic 
Brachiopoda in our Museum, which the Professor had figured and prepared for the press, 
and was on the point of publishing; but he willingly gave them up to Mr Morris, who was 
at that time contemplating a general description of the British Oolitic Mollusca. 
The anatomy of Brachiopoda had long been well known from the descriptions of our 
greatest Comparative Anatomist. But Professor M‘Coy was, I believe, the first to show the 
full physiological meaning of the muscles; which are not entirely homologous in function to 
the “adductor” muscles of other bivalves: but, on the contrary, constitute, in one portion 
of the animal, an apparatus for opening the shell. The discovery of this function (however 
minute it may appear) has a bearing upon a very large and difficult section of Paleontology. 
I may here remind the reader, that no specimens are figured in this volume but such as 
illustrate species that are new; or, at least, exhibit some new character, not well brought out in 
any published work with which the Author was acquainted. But every Paleozoic species in the 
Cambridge Museum, whether known or new, is carefully described: and every locality in which 
each species has been found (so far as can be made out from the specimens in the Museum) 
is distinctly enumerated. I may add, that the duplicates are preserved, and are arranged, so far 
as possible, in their proper subordination to the typical collection. This has been done for the 
express purpose of shewing the geographical distribution of the several species, and of assisting 
