Mr. Robert Garner's Malacological Notes. 373 



Clio above the oesophaguSj but tlie reverse in Hyalcea^ 

 Cleodora, and Pneumodermon. Fins are especially developed, 

 but only the rudiment of a foot; they swim rather than creep. 

 The high position here accorded them systematically rather 

 depends, it will be seen, upon type or external morphology 

 than upon structure. Eyes are to be seen iri' Hyalcea] and 

 Eschricht showed them to exist in Clio ; there are also dark 

 points on the cerebral ganglion of Cleodora^ which must be 

 corresponding organs. Garinaria^ though not considered to 

 be a pteropodous animal, can scarcely be better placed as a 

 Gastropod. In it the greatly developed vital or vegetative 

 organs of the mollusks generally are dwindled in bulk. The 

 pretty shell covering the viscera is curiously carried above the 

 elongated cylindrical body of the animal, which has caudal 

 and abdominal fins developed, the latter being the transmuted 

 foot, with a little sucker and pore at its posterior part. It has 

 very developed eyes ,• and we may observe little reddish ear- 

 sacs with their nerves floating internally behind and below 

 these eyes. 



As far as we have yet described, form rather than structure 

 has, in a few instances, faintly assimilated the Mollusca to 

 the Vertebrata ; but apparently we see a true structural ap- 

 proach to them in the Sepia. If there is any thing in the lower 

 mollusks which is a shadow of vertebrate structure or of a noto- 

 chord, we might fix upon the crystalline style, acting as a 

 fulcrum of locomotion, though its connexion with the stomach 

 and its gastric lamina remind us, on the other hand, of the 

 lingual plate and ribbon of the higher mollusks. Strange 

 modifications of an organ these, if they are such ! but organs are 

 curiously modified in many cases to perform different functions. 



There are in some carnivorous Gastropods, as well as in 

 Chiton &c., cartilaginous pieces supporting the lingual appa- 

 ratus ; and the cephalic ganglia of other species are enveloped 

 in an almost cartilaginous tissue. In Cephalopoda, besides the 

 shell, there are internal cartilages answerable to the internal 

 skeleton of the Vertebrata; the Sepia, for instance, has a 

 cartilaginous expansion, holding and supporting the brain, 

 eyes, and organs of hearing, besides giving passage to many 

 nerves and vessels, and having in front a trochlea for the 

 mediate tendon of a binocular muscle, the orbits still further 

 completed by supplementary laminse. There is another carti- 

 laginous lamina in front at the root of the arms, others in the 

 neck, and cartilaginous acetabula at the base of the siphon, 

 into which prominences of the mantle fit — a curious arrange- 

 ment to give the parts fixity during the respiratory movements. 

 There are also two lengthened sword-like cartilages at the 



Ann. & Mag. N. Hist. Ser.4. Fb^. xix. 26 



