246 



LIFE BY THE SEASHORE. 



KEY FOR IDENTIFICATION OF MOLLUSCA DESCRIBED 

 IN THIS CHAPTER. 



CHITONID.E, one genus, Chiton 



Surface of shells finely granular 

 Surface quite smooth. Colour red 

 Mantle with tufts of bristles . 



8 shells, 8 pairs of gills. 



C. margiiiatus. 



G. ruber. 



C. fascicularis. 



vulgatat 



(1) GASTEROPODA ZYGOBRANCHIA (shells cap-shaped). 



{Shell with strong \ p a t e 77 a 

 ridges . . . / 

 Sh a e nd Sate 8 ? 100 * 1 ! } ^kion pellucidum. 

 ' Shell with tortoise- ^ 



shell pattern in V Acmcea testudinalis. 



brown 



One gill present 



(2) GASTEROPODA AZYGOBRANCHIA (shells spirally coiled). 

 (a) Forms without a siphon. 



' T. cinerarius, 

 shell with 

 hole at 



Shells more or 

 less top-shaped 



Base flat, shell \ 

 pearly inside, f 

 whorls nu- I Trochus 

 merous. Ani- I 

 mal with cirri. J 



Shell thick, not ^ 

 pearly,whorls r Littorina 

 few. No cirri. ' 



Whorls 



base, 

 six whorls. 



T. zizyphinus, 

 no hole, eight 

 to ten whorls. 



L. littorea, shell 

 red or black, 

 surface ridged. 



L. oblusata, sur- 

 face smooth, 

 spire flattened. 



L. rudis, whorls 

 round, lip 

 thickened. 



Shells very long, J Whorls with \ 

 with many-! tubercles, 

 whorls . 



VU*/w4vJlvOj I 



outer lip ex- r Aporrhais pes-pclecani. 

 panded into I 



Shell very thin, -v 

 concealed, I 

 mantle with j 

 anterior notchl 



plate 



Lamellaria perspicua. 



