62 M. R. CARRIKER, D. B. SCOTT, AM) (i. N. MARTIN, JR. 



shell height; the length of the extended foot of the largest S. per- 

 spectivwn employed was 7.5 cm. These snails were held in iimning 

 sea water and 2;i\'en live hard clams, Mercendria mcrccnarki, for 

 food. 



To obtain incomplete bore holes of species in both families we 

 interrupted the snails in the act of penetrating live bivahe prey. 



Calcareous Substrates 



Selected areas of the smooth nacreous inner surface of the valves 

 of the oyster Crassostrea virginica, chiefly CaCOs in the form of 

 calcite (sometimes referred to as calciteostracum ) (Wilbur, 1960), 

 and the highh porcelaneous glossy inner surface of the univalve of 

 the muricid snail Murex fulvescens, mainlv CaCOa in the form of 

 aragonite, were used principallv as substrates in the studv of etch- 

 ings by ABOs. X-ra\' diffraction powder patterns were made from 

 samples of the outer prismatic and inner nacreous layers of C. 

 virginica and M. fulvescens; calcite was found in both la)'ers of the 

 former species, and aragonite in the latter. Etchings were also made 

 on the valves of the clams Dosinia discus and Spisula solicUssima. 



For nonbiologically formed crystals of CaCOs with no organic 

 matrix we used the flat, cleanly cleaved glossy surfaces of large pure 

 mineral calcite and aragonite crvstals. Polished surfaces of enamel 

 and dentin of cross-sectioned human teeth provided a calcium phos- 

 phate substrate in the form of hydroxy apatite crystals. 



Organic Substrates 



Preparation of demineralized conchiolin of mollusk shell is per- 

 formed without difficulty by suspending shell in a saturated solution 

 of EDTA ( disodium ethvlenediamine tetraacetate ) , pH about 6, in 

 a tall cylinder at room temperature. An o\ster valve 2.5 cm in 

 diameter may be decalcified in about 2 davs, leaving a highly trans- 

 lucent fiiTn gelatinous mass of conchiolin. 



Excision of ABO 



Removal of the muricid ABO was performed as follows. The shell 

 of the snail was cracked gentlv with a hammer over a brick without 

 tearing the soft parts, and shell fragments were removed with for- 



