PROF. AGASSIZ S 



[PLATK XXXVI CUTTLE Frsn.J 



upon the UUCK ; OUICMS in which ic is said ttiat the 

 gills are upon the sides, or on the lower side of the 

 animal ; and others in which the eyes are said to 

 be in an entirely different position from what is 

 observed in others. Indeed, no analogy has been, 

 nor can properly be traced between these animals. 

 I have, however, taken pains to trace analogy, 

 and if I am not mistaken, have succeeded in 

 making it out. But if I shall equally succeed in 

 satisfying you, is anotherquestion, which you may 

 decide after my illustrations have been made. Let 

 us begin with an animal well known in its form and 

 structure. Let us take the Oyster or the Scallop. 

 If we lift one shell, we see that it is lined inside 

 with a membrane called the mantle. The two 

 valves of the Scallop (Plate XLIV, fig. A) as you 

 see them drawn here on a large scale, are both 

 lined with the mantle. On opening these two 

 valves, you see the mantle on both sides. The 

 membrane, as it lines the valve of the right side, is 

 seen in Fig. B. The membrane which lines the 

 opposite valve, which is removed, and which cov- 

 ers the internal organs, is removed with the shell. 

 These two membranes lining the shells hang on 

 the two sides of the animal. So that the mass of 

 organs, the gills, the muscles, the liver, and alimen- 

 tary canal the whole structure is contained, as it 

 were, between those two folds those two mem- 

 branes as the contents of a sac within its walls. ! 

 Or I may compare the shell to the coat, the lining 

 membrane to the waistcoat, and the organs to the 

 body within. 



[PLATE XLTV PECTEN SCALLOP-SHELL J 



The position of the eyes is very remarkable in 

 this animal. There is a series of eyes (Plate 

 XLIV, fig. B) all around the margin of the mantle 

 about forty or fifty, or more, in number. And 

 you see that they occur upon both sides, so that 

 it is like a row of buttons along the coat, forming 

 here two rows of eyes, [laughter] ; and this posi- 

 tion 5s so extraordinary that we may not expect to 

 find any analogy with the Cuttle Fishes, (Plate 

 XXXVI. fig. A), where we have two large eyes up- 

 on the sides of the head, or with Strombus, as we 

 have in Plate XXXIII, where we have two large 

 eyes, upon peduncles, on the two sides of thepro- 

 [PLATE XXXIH STROMBUS.] 



