58 PROCEEDINGS OF THE MAIACOLOGICAL SOCIETY. 



chambers, the upper (posterior) one receiving the oesophagus and 

 bile duct, the lower (anterior) one loading out into the intestine. 



The intestine, after Leaving the stomach, passes bark underneath 

 the oesophagus for a short distance, then, curving on itself, passes to 

 the right side of the mantle, and, running parallel with the genital 

 duet, enlarges to form a glandular-walled rectum, which opens into 

 the anterior portion of the mantle - cavity. The liver is situated 

 in the centre of the visceral mass, and is entirely surrounded by the 

 genital gland; it pours its secretion into the stomach by means of 

 a bile duct, which enters the posterior chamber close to the opening 

 of the oesophagus. 



lladula. — Since there is a considerable amount of variation in the 

 radulse of different species of Turritetta, it will be of interest, for 

 purposes of comparison, to give a brief description of those forms 

 that have, up to the present, been investigated. In the majority 

 of cases the radula is typically tsenioglossate, having a formula of 

 2:1:1:1:2, each transverse row of teeth consisting of an 

 unpaired median, with a single admedian, and two laterals < 

 either side. 



The radula of Turritella communis, Kisso, has been described and 

 figured by Sars [8] (p. 185, pi. vii, fig. 1). The median tooth 

 is quadrangular in shape, the base being broad and straight, its 

 triangular apex is reflexed, the margin being provided with a large 

 central cusp bordered laterally by numerous smaller ones. The 

 admedian teeth are characterized by their finely denticulate free 

 margins. The laterals are sickle-shaped, their edges being serrated 

 in such a manner as to impart a feathery appearance to the tooth 

 when that is turned over and seen in surface view. 



The radula of T. ungulina, Linn. [Loven, 6], differs only in a very 

 slight degree from that of T. communis, llisso. The median tooth 

 is sub-quadrate, it is wider at the base than the apex, and its cutting 

 edge is finely denticulate. 



T. rosea, Quoy & Gaimard, is described by Hutton [4] as follows: — 

 "Length of central tooth rather more than half the breadth, the 

 reflected portion finely denticulated on each side, and with a larger 

 median cutting-point. First lateral [admedian'] finely denticulated 

 on the outer side ; second lateral much broader than the third, and 

 spoon - shaped at the tip ; both are finely denticulated on the 

 outer side." 



T. australis, Lam. (PL VI, Fig. 7.) So far as I am aware, the 

 radula of this species has not been previously figured. It is a very 

 small and delicate structure, and closely resembles the radula of 

 T. communis, Kisso, the chief difference consisting in the shape 

 of the median tooth, which has a somewhat convex base, its recurved 

 apex tapers, rapidly ending in a fine median cusp, the lateral edges 

 being finely serrated. The admedians are relatively large, the free 

 margin is denticulate, terminating in a moderately large cusp. The 

 lateral teeth are sickle-shaped, with finely serrated edges. Both 

 T. australis, Lam., and T. rosea, Quoy & Gaim., are forms having 

 a broad, shallow sinus in the outer lip of the shell; in this respect, 



