Mr, W. Clark on the Animals of the Ballida?. 101 



disappeared from the locality, and not one has been seen for 

 many years ; the animals now described were obtained near 

 Swanage, Dorset. 



The large circumferential canal of the separation of the up})er 

 and lower lobes is much more decided on the right than on the 

 left side, as from the former we have a view of the orifice of the 

 verge, the open seminal duct, and the common cavity of gene- 

 ration, the testis, and points of the branchias. The eyes are very 

 distinct, situate far back on the tentacular disk, and not very close 

 together -, they are black, and sessile in the centre of a minute cir- 

 cular lucid spot ; M. Cuvier has overlooked them. The fissure 

 of the mouth is vertical ; this is placed in the centre and' between 

 the tentacular and pedal disks ; and on each side the mouth, 

 within the groove, are two elegant conspicuous leaflets perfectly 

 symmetrical, each consisting of twenty strands on each side the 

 stem, which are largest posteriorly, and gradually diminish until 

 they are lost at some little distance from the buccal orifice by 

 suddenly turning inwards, appearing to pierce the groove and 

 enter the buccal cavity ; they are light yellow ; the one on the 

 right side is placed just above the seminal groove, the other on 

 the left in a symmetrical position ; the strands under the micro- 

 scope appear to be glandular, without a leading vein or artery ; 

 they have the aspect of minute, wiry, dendroid filaments. These 

 organs I should have taken for the salivary glands if M. Cuvier 

 had not stated the presence of others of a strap-shaped form in 

 another place, and as he has given nearly a similar form to the 

 salivary glands of the Aplysia, Helix aspersa and other herma- 

 phrodites, I must defer to such authority. I will return to this 

 point. I have now described all that can be seen without dis- 

 section. 



The vertical fissure of the mouth is faced by the anterior part 

 of the tongue, which consists of two hemispherical portions, each 

 furnished with fifteen obliquely arcuated yellow, wiry, horny 

 strands, set with short transverse hooks bending posteriorly. 

 This denticular apparatus does not extend through the large, 

 oval, pale red fleshy buccal mass, and is not supported by di- 

 stinct corneous plates, but by a tough coriaceous membrane. 

 From the posterior end of the buccal mass the oesophagus pro- 

 ceeds straight to the gizzard ; it is long, flat, broad and dilatable, 

 accompanied by the two straps described by M. Cuviei* as the 

 salivary glands, which are fixed to each side of the anterior and 

 upper part of the gizzard, and run on each side the oesophagus to 

 the posterior end of the buccal mass, to which also on each side 

 they are attached, apparently only to the external surface, and 

 do not appear to pierce it. Under the microscope they have little 

 appearance of being glandular or tubular, but have the aspect of 



