A striking complex of muscular bands controls the movements of the 

 radula in drilling . Circular and oblique bands maintain the general shape of the 

 odontophore and the buccal mass, and radial bands suspend the buccal mass in 

 position within the proboscis. Short muscular bands passing forward from the 

 odontophore to the tip of the proboscis, and very long bands extending backward 

 through the proboscis cavity into the cephalic region, function coordinatedly in 

 .alternately drawing the radula forward during each rasping stroke and retracting 

 it during the resting stroke. Likewise the radula is partly rotated on its long axis 

 to either side during drilling to effect a round smooth hole . In addition to the 

 tongue -like rasping motions of the radula, the radula itself moves back and forth 

 independently over the odontophoral cusion at each stroke . 



Two pairs of salivary glands are present in the forward confines of the 

 cephalic cavity. One pair empties its secretions into the dorsal part of the buccal 

 cavity, and the other into the true mouth. It is suggested that these secretions 

 function principally in lubrication, although biochemical tests may disclose the 

 presence of enzymes. 



Drilling in Uro salpinx appears to be aided by the softening action of the 

 secretions of the accessory proboscis which is located in the foot. This gland 

 was first discovered by Fretter (1941) in the two British drills, Nucella and 

 Ocenebra . The writer later discovered it in U. cinerea (1943). A minute con- 

 stricted opening leads into the shallow chamber which encloses the excessively 

 creased accessory proboscis. When everted in the living animal, this gland takes 

 the form of a translucent white rounded projection slightly larger in diameter than 

 that of the cephalic proboscis on the same drill, and with a height equal to the 

 diameter. At first Fretter (1941) believed that this gland was concerned with the 

 feeding process, but in a later paper (1946) she concludes that it is a sucker which 

 is used to maintain a steady purchase on prey during drilling. Her conclusions 

 are based on a histological study of the gland in the two British drills and in U. 

 cinerea, and on two observations with Nucella in which this gland was seen to 

 grip the shell of a mussel immediately below the spot at which the proboscis was 

 at work . She notes that the surface of the gland is covered by a very tall epithelium 

 composed of gland cells alternating with densely ciliated cells bearing short cilia . 

 The secretion from these gland cells is exuded as a dense sticky substance which 

 responds only slightly to stains specific for mucus. She also observed that in newly 

 hatched drills the accessory proboscis is relatively very large, possessing a 

 diameter equal to nearly 1/3 of the width of the foct Fretter writes further that 

 experiments (for which no details are given) with this gland show no solvent effect 

 on the shell of other mollusks However, studies which are being continued by 

 the writer and are summarized in the following paragraphs, strongly suggest that 

 the accessory probosics functions principally in the secretion of a substance which 

 softens the shell preparatory to rasping. 



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