88 



MALACOLOGY. 



French naturalists have erroneously called jaws ; they 

 are more properly to be designated teeth, performing 

 their functions, and their structure and mode of for- 

 mation are exactly similar to teeth. In, the Sepia, these 

 teeth act in direct opposition, in the Triton, hori- 



Triton Hambergii. 



zontally, in which case they are then surrounded at 

 their base by a thick circular muscle, pressing them 

 against each other when acted upon by the animal in 

 feeding. In the common snail, there is only one 

 tooth notched at its top, and it appears to serve as a 

 purchase, upon which the lingual mass or tongue of 

 the animal acts, not possessing any muscles to give it 

 action of itself, and remaining stationary for the time 

 required by the animal to eat, or rather lick the object 

 affording it sustenance, for which purpose the tongue 

 is admirably adapted, being thickly set with small 

 corneous bristles somewhat hooked, and of the cha- 

 racter of the tongues of the feline race. In ripe fruit 

 or other vegetable matter, this fact is clearly demon- 

 strated. In the Bulla, the hollow internal cavity of the 

 mouth, the upper part or palate is armed, like the 

 tongue, with minute corneous teeth. The headless 

 molluscs have no appearance of teeth whatever, but 

 the aperture of their mouths presents the character 

 of a lip, which is often prolonged into a tentacular 

 appendage." 



In the classification of molluscs, so as to form a 

 system of malacology, by the proper distribution of 

 their species, the same rules may be applied as with 

 every other type of animated nature ; it is quite clear 

 that nothing short of the whole organisation of any 

 animal can guide a naturalist in pronouncing the 

 proper order, class, or family, to which it belongs, by 

 affinity of parts ; and that the external characters of 

 the organs in these creatures must equally furnish 

 their distinctive positions in a systematic arrangement, 

 as with animals more exalted in the scale of creation. 

 In malacology one great distinction may, however, 

 be drawn ; the general organisation of the animal is 

 often well characterised by the form of its shell, and 

 that indication has induced many naturalists of the 

 old school to imagine a knowledge of the one suffi- 

 cient to acquire the other ; but this error we have 

 endeavoured to rectify in the article before us, and 

 we will now add some further proofs of the fallacy of 

 that opinion, and of the necessity of taking many 

 other objects into consideration, to which end we 

 cannot do better than quote extracts from the opinions 

 of Cuvier, Lamarck, and other naturalists, who have 

 founded, and brought to its present state of perfection, 

 the system of malacology ; but we shall only do so 

 where those opinions concur, and are sanctioned by 

 living naturalists, as the differences that have, and 

 must always exist on matters but little known and 

 difficult of access, could not either interest or instruct 

 that class of our readers whose minds are only dawn- 

 ing to a love of the study of nature and the Almighty 

 giver of life ; such as have advanced more deeply into 

 that delightful pursuit, having overcome its first diffi- 

 culties, and seeking to disco ver more from the inexhaust- 



ible store it presents to an inquiring mind, must either 

 look for assistance in the detached labours of scientific 

 men who are pursuing a similar course, or strike out 

 tor themselves an untrodden path : our pleasant task 

 is ended, when we have, to the best of our ability, 

 amassed together everything we deem usefully 

 instructive in this branch of natural history, and con- 

 densed it to the smallest space capable of conveying 

 our meaning, or that of the high authorities we have 

 quoted. 



A consideration of the precise spot orparticular coun- 

 try inhabited by molluscs can be of very little import- 

 ance as a guide in their classification, as their locality is 

 not indicative of the form of the animal or its scientific 

 arrangement. We cannot, like the good old Izaac Wal- 

 ton, say, while walking by the river side, here we will 

 rest and take a shell of such a description, as he was . 

 wont to say of a chub or a trout, without having a previ- 

 ous knowledge that such things were to be found at that 

 spot. The peculiar kind of subsistence these animals 

 require cannot either have much influence, because, 

 though it is possible to imagine a certain correlation 

 of organs visible, and the structure of the digestive 

 apparatus more or less modified for some one parti- 

 cular alimentary substance, that never is the case, as 

 far as every examination or reason can extend, and 

 we have indeed a proof that no such provision of 

 nature exists, since we find species essentially carni- 

 vorous, as the Tcstacella, of the same order as the 

 slug, which is completely herbivorous. The existence 

 or absence of a calcareous protection or shell, is evi- 

 dently of very considerable importance to a scientific 

 arrangement.sincethatconstitutes awell-defined appa- 

 rent external character ; a knowledge of them will, 

 however, furnish proofs, though the exceptions are not 

 numerous, of conchyliferous animals being of the 

 same genus as others completely divested of shell, 

 such as the Bulla and the Lobaria, the Bursatella and 

 the Dolabella, 



The particular form of the animal's body, where 

 the visceral portion is more or less spirally elongated, 

 is also of very little importance, as we have seen 

 examples of the snail, in which the whorls were drawn 

 out like a watch-spring, not touching each other in 

 their convolutions. The lobes, cirrhi, and other ap- 

 pendages, which border the mantle, are not very 

 important to consider, if we except the order Lamclli- 

 branchiata, where a consideration of the tubular 

 lobes, by which the mantle is prolonged backward, 

 present extremely useful characters. The animal 

 possessing a perfectly or imperfectly formed head, or 

 none at all, constitutes the different divisions of the 

 first order of malacology ; but these characters are 

 not always very distinctly defined. The form, position, 

 and number of the tentacular appendages of the head, 

 present a more essential and certain character to 

 study in the establishing a classification of molluscs ; 

 some anomalies are nevertheless observable and alto- 

 gether inexplicable ; in the Caryclrium, for example, 

 the true tentacula gradually disappear, while other 

 animals of the same family have them strongly pro- 

 duced. The position of the eyes is a consideration 

 of some consequence, but probably less so than the 

 tentacula, nevertheless it forms no constant guide, as 

 genera of their family, and even species of the same 

 genus have subpedunculated eyes, and others have 

 them sessile. The principal organ of locomotion, 

 that is the foot of the animal, and the natatory appen- 

 dages, are of very considerable value in classification, 



