GALVINELLA. 27 



followed by eight simple lines of three to six cerata each. The outermost cerata are 

 small, cylindrical and straight ; the inner are 5-6 mm. high, and nearly always curved 

 almost into a semicircle. Four of the cerata stand in the middle of the back, two in 

 front of the pericardium and two behind. Though a few of them have been lost, they 

 are not caducous. 



The anus is a prominent medio-dorsal papilla, standing just behind the 

 pericardium and after the fourth row of cerata. The jaws are thin and yellowish. They 

 are not denticulate, but present near the edge an appearance like a tessellated pavement 

 due to numerous short prominences. The radula consists of sixty-four rows containing 

 three teeth each. The central tooth (fig. 29) bears a median cusp, and on each side of 

 it four denticles, of which the fourth is less conspicuous than the others and sometimes 

 absent. The median cusp is fairly strong, but rather low and points straight forward, 

 whereas the first of the lateral denticles often points distinctly upwards. The side 

 denticles are fairly long but a little irregular in shape and direction. The lateral teeth 



FIG. 29. Galvinclla antarctica CENTRAL TOOTH; a FROM FIG. 30. Galvinella antarctica 



BELOW; 6 FKOM ABOVE. LATERAL TEETH. 



(fig. 30), are much as in Galvina, very thin and transparent but distinct. The base is 

 very long and bears a single pyramidal cusp, the tip of which is often broken off. 



The rest of the digestive system appeared to be as usual. The salivary glands are 

 long, simple bands. Flocculent ptyaline glands also seem to be present. The central 

 nervous system is as usual. The cerebro-pleural and pedal ganglia are both spherical, 

 the latter distinctly below the former. The olfactory ganglia are elliptical. The eyes, 

 which are black with yellow lenses, are set far back on the cerebro-pleural ganglia. 

 The reproductive system also appeared to be as usual. The hermaphrodite gland is 

 not large, but the lobules which compose it are very distinct and consist of small 

 spherical bodies set round a large one. The verge is long, conical and unarmed. 



VOL. II. 



