170 The Molluscan Family Planorhidae 



Digestive System. The digestive system is like that of the Heliso- 

 matinae in general. The stomach region is rather narrow and resembles 

 that of Promenetus exacuous figured on plate 48 (figs. 4, 5). There is a 

 large blind sac or caecum. The intestine makes a coil about the stomach 

 and another around the liver. The buccal sac is pyriform, elongated, with 

 a short, rounded radula sac. The salivary glands are short and are com- 

 posed of large branched follicles, in this respect diff'ering from the salivary 

 glands of Helisoma. 



The superior jaw (plate 50, fig. 14) is wide and low. convex, the ends 

 attenuated and bent downward. The face of the jaw is heavily vertically 

 striated. The side jaws are very narrow and as long as the width of the 

 superior jaw. 



Radula (plate 66, fig. 2). Center tooth higher than wide, the two spade- 

 shaped cusps not reaching the lower margin of the base of attachment. 

 Lateral teeth (1-9) squarish, tricuspid, the cusps sharply pointed, the 

 mesocone larger than either the entocone or ectocone. Intermediate teeth 

 (10-14) narrower than the lateral teeth, the entocone breaking up into two 

 to four sharp, pointed cusps, the ectocone becoming bicuspid. Marginal 

 teeth (15-38) narrow, the entocone breaking up into five to six subequal 

 cusps, all in a straight row, the ectocone becoming tricusind, the cusps very 

 small. The mesocone remains large in all teeth with but little modification. 

 The outer marginals (39-42) are very narrow, much smaller than the other 

 marginals, the cusps becoming very small and forming a serrated outer 

 margin of the teeth. 



Germain (1931, p. 518) figures the radula of corneus as having inter- 

 stitial cusps, but such were not observed in the material personally ex- 

 amined. Taylor (1900, p. 270) figures the laterals as bicuspid and in this 

 he is followed by Simroth (1912, p. 316). All specimens studied have had 

 tricuspid lateral teeth, as has been noted for every genus in the family as 

 yet examined. Taylor also figures thirty-three teeth in a row while in 

 specimens personally examined the number has been from forty-two to 

 forty-five. In some specimens from Germany, there were odd teeth (72nd 

 row, 12-15, marginal) in which the cusps of the endocone were uneven 

 and the smaller ones might be assumed to be interstitial cusps. Some outer 

 marginals (17, 20, 22) were of a like nature. 



The following radulae have been examined: 



Locality Formula Rows Source 



Poland, near Warsaw 42-1-42 200-217 Mr. A. Jankowski 



Germany 45-1-45 170-210 Dr. F. Haas 



Florida (aquarium specimen) 45-1-45 200-218 Mr. Roger P. Gray- 



Material from the following sources has been used for the above data: 

 Branch of Wista River at IVIorysinek, 5 km. south of Warsaw, Poland, col- 

 lected by Mr. A. Jankowski; Germany (locality unknown) from Dr. F. 

 Haas; Ojus, Florida; Copenhagen red snails, bred for aquaria, Air. Roger 

 P. Gray, sent by Air. T. Van Hyning. 



Geographical Distribution, Great Britain and Europe east to northern 

 and western Asia, south to Portugal and Italy. It has been introduced into 

 New Jersey, Puerto Rico, and probably other places. Whether the larger 

 species found in northern Africa are referable to Planorbarius can only be 

 determined bv an antomical examination. 



