134 GASTROCHiENID^. 



architecture. On the subject of these cases, there may be 

 found an interesting paper in the sixth A'ohime of the 

 " Magazine of Natural History,"" written by JNIr. Lukis, 

 a gentleman from whose cabinet. Dr. Turton derived a 

 considerable portion of his information upon the shells of 

 the Channel Islands. From that paper we extract the 

 following sentences, which are equally applicable to the 

 case we have figured (from Ireland,) as to the Guernsey 

 individuals, from which the somewhat rude wood-cuts re- 

 ferred to in the text were sketched : " In a country des- 

 titute of limestone or soft rock, these animals are indebted 

 to other means for supplying them with a habitation. The 

 G. pholadia accommodates itself to crevices, not the interior 

 of rocks, where it forms its residence by covering its shell 

 as here exhibited. It is found among madrepores and 

 shelly fragments, thrown up with alluvial sand and rubbish 

 on the sides of rocks. The cases here shewn are composed 

 of broken shells and gravel, mixed with fragments of felspar, 

 hornblende, and sand, (these latter substances are not 

 present in our own examples,) strongly agglutinated toge- 

 ther. The inside is smooth, and consists of thin layers of 

 the calcareous secretion applied by the animal in the 

 formation of this chamber, which somewhat resembles a 

 flask ; the lengthened neck through which the animal 

 passes the double tube, is formed of concentric layers of the 

 same substance, preserving to a certain depth, the same 

 figure as at the summit of it." 



The animal of GastrochiEna modiol'ma was first observed 

 and figured by Delle Chiaje. It has recently attracted the 

 attention of Philippi and of Deshayes, both of whom have 

 published figures and accounts of its structure, external and 

 internal. On the British shores it has been carefully ex- 

 amined by Mr. Clark. The body is claviform, broad 



