154 ON THE MORrHOLOGV OF THE CEPHALOUS MOLLUSCA 



Attached by a narrow root or pedicle to the ventral surface of the 

 cylindrical body is the broad cheese-cutter-shaped foot, or as I pro- 

 pose to call it, propodium {pp). Its posterior edge is quite sharp, and 

 carries no sucker-like expansion. The anterior fifth, or thereabouts, 

 of the animal is thinner than the rest of the body, and it narrows 

 again towards its extremity, which is truncated, and forms a circular 

 lip round the aperture of the mouth. Just behind the narrowed fifth, 

 and towards the dorsal surface, we observe the eyes, and immediately 

 below, and as if proceeding from them, are the tentacles, which are 

 short and conical. 



The posterior extremity also is abruptly truncated ; its uppermost 

 angle slightly projects, and viewed from above appears like a sub- 

 spiral, richly ciliated band {d). Some little distance from this is the 

 aperture of the anus {a). 



From the two inferior angles, two tubular processes pass in the 

 male (fig. i). The right process ends in a globular body and is the 

 penis (/), while the left (which I shall call the metapodiuni) is long 

 and somewhat pointed ijni). 



In the female there is only one process (the metapodium) (figs. 2, 3 

 vit) answering to the left of the male, but a long cylindrical egg-tube 

 frequently trails from the aperture of the oviduct (fig. 2). 



Alimentary System. — This consists of, — i, the buccal mass ; 2, the 

 cesophagus and stomach ; 3, the intestine and its termination, the 

 rectum ; 4, the liver ; and S, the salivary glands, which are very small 

 and placed above the buccal mass, contrasting singularly with the 

 very large salivary glands oi Atlanta. 



The cesophagus, stomach, and intestine form a straight tube running 

 through the axis of the animal, and suspended by a ligament to the 

 donsal parietes (fig. i) ; having reached the "nucleus," that is, the 

 mass of the liver and ovary, the intestine bends up at a right angle, 

 and so becomes the rectum, which terminates, as has been seen, upon 

 the dorsal surface. 



The Buccal Mass, or Tongue (fig. i b). — This is an oval brownish 

 body, placed below the commencement of the oesophagus, and forming 

 the floor of the cavity of the mouth. The following parts may be dis- 

 tinguished in this mass : — 



1. Two ovoid compressed masses of thick-walled clear cells, which 

 somewhat resemble cartilage. I shall call these the " lingual car- 

 tilages." 



2. These give attachment to muscular fibres by their outer surface, 

 and are enveloped in them. One portion of these fibres is inserted 

 anteriorly into the parietes of the body, and acts, therefore, as a 



