DR. LEIDY.— MISCELLANIA ZOOLOGICA. 69 



muscles, the physical properties alone of the ligamenta spiralia, in resuming their 

 unstretched state, close the wings. These ligamenta spiralia are numerous, and exist 

 in all the species of Locusta possessing perfect al© which I have examined. To this 

 short description I append a drawing of several of these ligaments, magnified, from a 

 preparation in Canada balsam, of one of the alse oi Locusta Carolina. 



3. On the situation of the olfactory sense in the terrestrial trihe of the 

 Gasteropodous Mollusca. * 



While no observer of the habits of the terrestrial Gasteropoda, doubts the existence 

 of the sense of smell in them, but on the contrary, asserts positively that it does exist, 

 the anatomist heretofore has not been able to point out its precise seat. 



Swammerdam, in his Biblia Naturae, speaks decidedly of the existence of this sense 

 in Helix pomatia, but offers no conjecture as to its situation. Blumenbach remarks, 

 under the head of Vermes, " Several animals of this class appear to have the sense of 

 smelling : as many land-snails {Helix pomatia, &c.,)" and afterwards adds, " But the 

 organ of this sense is hitherto unknown ; perhaps it may be the stigma thoracicum." 

 Cuvier, in his " Memoire sur la Limace etle Colimaqon," after remarking the delicacy 

 of this sense, thinks it probable it may reside " Dans la peau toute entiere, qui a 

 beaucoup de la texture d'une membrane pituitaire." 



In investigating this tribe of mollusca, I detected an organ which appears to have 

 been entirely neglected, or has escaped the notice of those who have dissected these 

 animals. It is a depression or cul-de-sac, having its orifice beneath the mouth, 

 between it and the anterior extremity of the podal disk, and which in a number of 

 species of different genera is elongated backwards into a blind tube, more or less 

 deep, free, and occupying a situation just above the podal disk within the visceral 

 cavity ; in others it is a funnel-shape depression, excavated in the substance of the 



*Proceed. Acad. Nat. Sci. vol. iii. p. 136. 

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