446 Mr. W. Clark on the Conovulida?, 



always outruns it a little ; it is therefore between the neck- veil 

 and the foot this organ anteally forms two curved lobes, caused 

 by the deep indentation in its centre. The pedal disk is mode- 

 rately long and rather broad, divided transversely very deeply 

 at a third of its length ; the other two-thirds taper gradually to 

 a moderately rounded termination, sometimes slightly emar- 

 ginate and with a medial groove ; the pedicle of attachment to 

 the body is long and slender. The structure of the foot is that 

 of Pedipes ; I observed it tw^enty-five years ago, and its quality 

 of locomotion perfectly agrees with the etymology of that term ; 

 it is very slow in consequence of a double action of the pedal disk 

 being necessary to effect progression, the anteal portion being 

 first carried forward, accompanied by the head and neck, and is 

 then fixed, when the posterior portion carrying the shell is drawn 

 up to its predecessor ox pes pedi and so on, and thus a slow march 

 is accomplished : there is no operculum . The neck, from the 

 length of its protrusion, admits of close examination, but no ge- 

 nerative organ was observed. I think that from all the fourteen 

 specimens having ovaria, they, like the Helices, are hermaphro- 

 dites with mutual congression. The sac of the ova is deposited 

 in the posterior cavity of the shell, which part is without internal 

 spire ; the animal appears to have the power of absorbing the 

 septa ] the oviduct winds entwined with the brown liver, accom- 

 panied by the intestine to its termination at the middle of the 

 right side of the aperture. The intestine is by far the most con- 

 spicuous organ of the viscera ; it is very large and always fully 

 distended ; its course after leaving the pylorus of the bursiform 

 stomach is along the left side glued to the liver ; it descends to 

 nearly the ovarian bag before it ascends on the right side of the 

 liver to its termination at the middle of the aperture, where the 

 fsecal matters may be seen to issue, not in distinct pellets, but in 

 large cylindrical-formed brown sandy masses ; the rectum is a 

 mere aperture, but, like the intestine, of large calibre ; there are 

 two slight sigmoid flexures, otherwise the form and course of the 

 intestine and its formed contents are very similar to those parts 

 in Helix ; the oesophagus is long, but though we could not de- 

 tect all the organs of the buccal mass, we found at the usual place 

 the nervous cordon of two oval yellow ganglions. 



I now come to the most important point of this examination, 

 the character of the respiratory organ, as some malacologists are 

 still in doubt whether the animal breathes pure air or extracts it 

 from water; my own prepossessions have been of the latter cast. 

 Having submitted fourteen live animals to the powers of an ex- 

 cellent microscope, I am enabled to say, that I found no traces 

 of a regular pectinated membrane ; but when the dissection turned 

 out well, there appeared, as in the usual place of the Helices, what 



