Mr. W. Clark on the Chemnitzia?. 109 



long, cylindrical, like that of the Chem. spiralis, and finely trans- 

 versely corrugated, ending at the tentacula, which, though some- 

 what apart, are united by the usual membrane of the Chemnitzice ; 

 they are thick, broad, short, not very membranous, rounded at 

 the tips, which have the characteristic minute flake-white lobe or 

 inflation. The black eyes are not very near together ; they are 

 immersed exactly and close to the base of each tentaculum on 

 minute white circles ; they do not in the least invade the area of 

 the neck, but rather impinge on the stamens of the tentacula. 

 The effete muzzle or mentum is undoubtedly the continuation of 

 the neck, and has no connection with the foot, which position I 

 propose to show in a separate work ; it is long, slender, grooved 

 at the margins anteally and on each side, the upper and lower 

 surface being perfect and unbroken ; the vertical fissure of the 

 mouth is under the tentacular awning. The foot is of the palest 

 frosted yellow, exceedingly short, narrow, deeply bifurcated in 

 front, at rest rounded behind, and a little lengthened in action. 

 The animal examined was an " Alma Venus," and when fully re- 

 tracted occupies the fourth volution ; then the light green liver, 

 and very pale red granular ovarium, occupy the three primary 

 volutions ; but when the animal is fully out in the body of the 

 shell, the liver and ovarium are altogether withdrawn from the 

 first whorls, leaving them perfectly hyaline, and they are then 

 deposited in the lower part of the third and the whole of the 

 fourth volution, the other parts of the body and organs being in 

 the fifth and sixth. The narrow arcuated branchial plume of 

 about 15-18 rather coarse, opake, pale drab strands, and with 

 the auricle and heart, distinguished by their intense snow-white 

 colour, is perfectly visible, under a powerful Coddington lens, 

 at the smaller and posterior end of the branchial plume. I have 

 been thus particular as to the site of the organs, because I never 

 met with a shell so perfectly hyaline in which their position 

 could be so well seen. The operculum is an almost invisible 

 film, pear-shaped or suboval, with a narrow border of pale bistre 

 with a pinkish hue ; the striae of increment radiate as in most of 

 the other Chemnitzice ; it is fixed on a plain lobe near the pos- 

 terior extremity. I saw no ornamental appendages to the head 

 and neck. In this example the apex is subreflexed, and there is 

 a rudimental denticle on the pillar lip. Axis y 1 ^, diameter & 

 uncise. 



This very rare animal is an undoubted Chemnitzia, and pro- 

 bably the first of the species that has ever been seen alive. To 

 add to the interest of this little narrative, I state, that Mrs. Gul- 

 son, who last year allowed me the honour of attaching her name 

 to this elegant shell, examined and saw her namesake in a living 

 state. 



