126 MALACOZOA. GASTEROPODA. PECTINIBKANCHIATA, 



2. Ndtica rutila. Ruddy Natica. 



Shell subglobose, rather broader than high, thick, glossy ; 

 with the spire very short and convex; the suture channelled 

 but narrow ; the turns four, very convex, transversely striulate, 

 the last turn ventricose; the aperture oblique, subovate, its 

 inner side nearly straight, the outer lip thin, the inner thick- 

 ened, slightly reflexed at the umbilicus, but not forming a pro- 

 minence there ; the umbilicus strongly sulcate ; the colour dull 

 greyish-red, with a white band margining the suture, at which 

 the margin of the turns is sharply inflexed, the base of the 

 shell paler, the inside reddish-white ; operculum semicircular, 

 horny, spirate. 



This species does not agree with any that I have seen de- 

 scribed ; but seems to be intermediate between Natica moni- 

 lifera, and Natica rufa of Montagu. It was found in October, 

 1842, by Mr. Alexander Murray, at Fraserburgh. 



3. Ndtica Alder i. Alder's Natica. 



Shell subglobose, rather thick, highly glossed ; with the 

 spire very short and rather acute ; the suture simply linear, 

 with the edge of the turns closely overlying ; the turns five, 

 very convex, faintly striate transversely, the last turn ventri- 

 cose ; the mouth oblique, semicircular, the outer lip thin, the 

 inner partly covering and narrowing the longitudinally striated 

 umbilicus with a mass of white callus ; the colour light reddish- 

 yellow, with an undefined band of yellowish-white along the 

 margin of the whorls, another from the umbilicus to the 

 mouth, and on the last turn five series of red spots, generally 

 alternating with white or whitish spots ; a brown band enter- 

 ing the umbilicus, and a brown spot or band on the callosity 

 of the inner lip. Length half an inch, breadth about the same. 



The ground-colour varies from yellowish-white to orange- 

 red, and the spots are linear, square, roundish, direct or oblique, 

 curved, angularly bent, sagittiform, or even cruciform. Fre- 

 quently the bands are articulated with white, or the red spots 

 seem painted on a white band. Individuals sometimes occur 

 without markings. 



This species, very nearly allied to Natica monilifera, may be 

 distinguished by its having the spire much less convex, the 

 general form less globose, the umbilicus narrower and com- 

 pressed by the callus. The red spot or band on the callus is 

 not distinctive of this species, for it occurs occasionally in 

 both. 



