222 PHOLADID. 
has been mentioned under the heads of the organs I have 
described, except those of the ovary, which will be noticed 
hereafter. These animals, like all the Bivalves, are strict 
hermaphrodites. The ovartum is a white glandular body 
entwined with the liver, but as it approaches the pericardium 
it becomes a distinct mass; and, what is unusual at this time 
of the year (20th January), in several of the ovaria the contents | 
had begun to assume the appearance of ova; but with the 
utmost power of the microscope I could not perceive any 
trace of the membranous pyriform bodies containing a fluid 
which I have observed in the genial months in many of the 
ovaries of the strict hermaphrodite Bivalves and Gastero- 
poda, which I consider to be the male influences; nor could 
I discover any other organ that had the slightest pretension 
to be regarded of a similar nature. I failed to verify the 
oviduct, but from the position of the ovarium I have little 
doubt that it passes at and under that portion of the peri- 
toneal cavity which contains the terminus of the ovary, into 
the anal compartment of the mantellar tube, about 14 inch 
above the siphon, and that the ova are there discharged. 
I do not think the branchiz in this species serve as re- 
ceptacles for the ova; their structure is not calculated for 
such purpose. 
I will now make a few observations on the camerated 
structure of the posterior part of the protective tube, which 
has caused malacologists much speculation on its uses; some, 
myself amongst others, thought the lamimar spaces might 
be to protect the pull for a time until ultimate exclusion. 
These ideas were dispelled by the discovery of the fixture of 
the posterior part of the animal by the strong oval muscles 
springing from the sphincter, which induced me to examine 
this portion of the tube with care, and m a fine full-grown 
specimen I discovered the principal object, if not the precise 
animal ceconomy, of the laminz. I perceived in the centre of 
each plate a decided muscular impression, which, on compa- 
rison with the last-formed one of the sphincter muscle, proved 
to be-identical in shape ; this fact made it evident, that the 
animal, either when full-grown, or when growing, if its longi- 
