89 



Mr. S. H. Scudder offered some remarks upon the mouth-parts of 

 articulated animals, with especial reference to those of Insects. He 

 showed that these parts were composed of several pairs of jaws which 

 worked laterally, and not, as in the vertebrates, vertically. In some 

 insects they took the simple form of biting jaws ; in others, that of 

 a sucking tube, composed sometimes of one, and sometimes of another 

 pair of jaws ; in some cases, this tube enclosed within itself the other 

 pairs of jaws, modified into piercing needles or double-bladed lancets, 

 and moving upwards and downwards through the tube. All these 

 varied forms were shown to be constructed upon a single type. Prepa- 

 rations of different insects, illustrating these points, were exhibited 

 under the microscopes. 



Mr. Edward S. Morse called attention to the preparations of snails' 

 tongues under the microscopes, and then explained the various modes 

 in which the MoUusca procure their food. 



There were three prominent groups in the Mollusca ; the Acephala, 

 the lowest, had the simplest form of mouth, a mere slit, without any 

 hard parts for biting or triturating the food. Their food was of a 

 microscopic chai'acter, and by means of ciliary action was swept to 

 the mouth, having previously been drawn within the mantle by the 

 currents of water which bathed the gills. 



In the Gasteropods the mouth is generally furnished with a bitiug- 

 plate on the upper lip, and a tongue armed with a multitude of sili- 

 cious particles ; and with this tongue the food, consisting in some 

 of vegetable matter, in others of animal substances, is rasped, and thus 

 reduced to a state fit for the stomach. 



In the highest of the Cephalopods, the mouth is armed with a for- 

 midable set of jaws, in form and arrangement like a parrot's beak. 

 With this armature, animals of large size often become an easy prey. 

 They have a tongue similar to the Gasteropods, and, in addition to 

 this, they have powei'ful arms surrounding the mouth, with which 

 they seize and hold their prey while in the act of feeding. 



Mr. Alpheus Hyatt next explained the structure of the mouth and 

 stomach in the Radiates and lower animals known as Protozoa. In the 

 highest radiates, he showed that teeth existed, as in the sea urchin 

 (Echinus) ; and how in the polyps and jelly-fishes the mouth was a 

 soft-lipped orifice, destitute of hard appendages. 



He described the relations of the stomach to the mouth-parts, and 

 the gradual simplification of the whole digestive apparatus in the 

 lower Radiata and Protozoa, until they ceased to be present at all in 

 the Amoeba, which opened the external wall of the body at any con- 

 venient point, and took in its food. 



Thus, by the remarks of the several speakers, we were gradually led 



PROCEEDINGS ESSEX INST., VOL. V. 12 AUG., 1867. 



