224 Olive B. Davies: 



cular, more especially so at the posterior end, where they form a 

 rounded muscular pad. Two stout muscle bands are attached to 

 the dorsal surface of the posterior end of tlie pharynx, and their 

 other ends to the columellar muscle; these assist in the contraction 

 of the pharynx. .V number of protractor muscles ai'e attached to 

 the anterior end of the pharynx, and at their other ends to the 

 walls of the anterior end of tKe body and head. 



If the pharynx is opened from the side, the radula can be seen 

 lying on a muscular band, which anteriorly becomes developed into 

 a pad. Attached to this pad are special muscles, connected with the 

 roof of the pharynx, which assist in the forward and backward 

 movement of the radula. There is no jaw. The raduia is large, as 

 is usual in the carnivorous land mollusca. It consists of about !>8 

 rows of approximately 118 strong, sickle-shaped teeth, eacli with u 

 very sharp pointed end and a broadened base, the base being pio- 

 duced in a little knob on the inner side of the sickle, and in the 

 outer teeth being almost quadrate in shape. There is no rachidian. 

 The uncini are larger than the laterals, and of the uncini them- 

 selves, those towards the centre are not so large as those near the 

 outside, but the two or three most external become smaller again; 

 this last feature is more marked in P. at ra men f aria than in P. coin- 

 jmcta. Where one would expect the rachidian, there is a clear 

 space, and on either side of this are teeth much smaller than the 

 laterals, and arranged irregularly; beyond these are the laterals, at 

 first placed almost straight and later becoming more and more 

 triangular till we come to the marginals. I measured the radulas 

 of the two species. That of P. cortipacfa was 18 x 4 mm., and /'. 

 atramentaria was 20 x 5 mm. The teeth are of the same general 

 type in both species, the differences may be seen in Plate X\II., 

 Figs. IX. A. and B. iMr. Suter has given the dental formula for 

 P. atramentaria as 50.1.5U. I could not find any rachidian, but 

 down the centre of the radula is the clear space I have mentioned 

 above, and to eithei- side of this the irregularly arranged teeth, 

 about one-third the size of the adjacent laterals. I also, in my 

 specimen, counted at least 56 teeth on each side of tlie central 

 space, but could not be sure of tlie exact number, as the radula 

 was slightly torn at the mai-gin. 



The oesophagus leaves the pharynx from its dorsal surfaie, about 

 one-third of its length from its anterior end. It runs as a straight, 

 narrow tube for some distance, and then widens slightly to form 

 the stomach. The canal then twists round, as tlu- intestine, under 

 the stomach, and (.•ontinues running through the liver and finally 

 twists back to run along the right edge of the pvdmonary chamber, 

 and opens to the exterior at the pulmonary opening. 



