360 AMERICAN JOURNAL 



"1st. Polyzoa: dorsal attachment. 

 2d. Brachiopoda: dorsal and anterior attachment. 

 8d. Tunicata: anterior. 



4th. Lamellibranchiata: anterior and ventral attachment. 

 5th. Gasteropods : ventral and posterior attachment." 

 6th. Cephalopods: free. 



The following remarks are made on the mouth and foot : — 



"In the Lamellibranchs the foot is a simple muscular organ, 

 developed from the ventral surface and protruding anteriorly. 

 It is simply an organ of locomotion, in the lower forms not 

 even performing this function. The oral opening is a simple 

 slit, without the power of seizing or triturating its food. 



" In the Gasteropods the foot is more specialized, and as an 

 organ of locomotion far superior to that of the Lamellibranchi- 

 ates, having oftentimes three well characterized regions, called 

 by Huxley, the pro- meso- and metapodium, these regions 

 oftentimes supporting certain processes, e.g., cirri, opercula. 

 The foot not only performs locomotion, but in many cases has 

 the power of seizing -and retaining its prey [e. g., Natica), The 

 mouth has an apparatus for biting and triturating its food, 

 being famished with an upper jaw, or buccal plate, and a 

 tongue, armed with silicious particles. In the Cephalopoda 

 the foot is so far differentiated as to be separated into prehen- 

 sile arms furnished with rows of suckers, or hooks. These 

 arms surround the head, and are thrown directly forward. 

 They are capable not only of locomotion, but of seizing their 

 prey, and performing also movements of aggressive action. 

 In the higher forms of Cephalopods, the function of locomo- 

 tion is delegated to other organs, while the arms subserve the 

 uses of the head alone, and the mouth, furnished with two 

 powerful mandibles opposed vertically, forcibly reminds us of 

 a parrot's beak, or that of certain other vertebrates. Thus 

 we have cephalic power manifested in the mechanical action 

 of the foot. 



" 1st. Lamellibranchs — Locomotion. 



"2d. Gasteropods — Locomotion, Prehension. 



"3d. Cephalopods — Locomotion, Prehension, and Aggress- 

 ion. 



"According to the principle of Cephalization, cephalic 

 power is manifested either as a mechanical, sensorial, or pyschi- 

 cal force. Thus the Cephalopods possess, in the greatest mea- 

 sure, all threa; while Gasteropods, not indicating, to any great 

 extent, aggressive action, may be said to manifest but little 

 psychical power ; and the Lamellibranchiates manifest essen- 

 tially only mechanical action." 



