76 PROCEEDINGS OF THE ACADEMY OF [Marcll, 



helpful suggestions, and to Miss Helen Winchester for care exercised 

 in making the drawings. In addition the writer wishes to especially 

 acknowledge the kindness of Mr. Charles W. Johnson, of the Boston 

 Society of Natural History, in giving him much valuable information 

 in regard to the range and distribution of the races and species. 



Explanation of Plate II. 



Fig. 1. — Volutilithes limopsis Conrad. Matthew's Landing, Ala. Adult of 

 moderate size showing the persistence of the cancellated stage throughout 

 the later whorls. Length = 18.5 mm. 



Fig. 2. — Volutilithes rugatiis Conrad. Matthew's Landing, Ala. Young individ- 

 ual showing the cancellated stage. With the exception of the last whorl, 

 the sculpture is very much like that of V. limopsis. Length = 19.5 mm. 



Fig. 3. — Volutilithes petrosus Conrad. Bell's Landing Race. Bell's Landing, 

 Ala. Young individual showing the cancellated stage. Length = 20 mm. 



Fig. 4. — Volutilithes petrosus Conrad. Jackson Race. Jackson, Miss. Young 

 individual showing the cancellated stage. Length^lQ mm. 



Fig. 5. — Volutilithes petrosus Conrad. Gregg's Landing Race. Gregg's Landing, 

 Ala. Adult individual showing the general characters of the V. petrosus 

 main stock. The later whorls show the spiny stage. Length = 50 mm. 



Fig. 6. — Volutilithes petrosus Conrad. Yellow Bluff Race. Yellow Bluff, Ala. 

 Adult individual showing the general characters of the V. petrosus main 

 stock. This is, however, not as typical an expression of the features of the 

 main stock as is seen in fig. 5. The later whorls show the spiny stage. 

 Length = 44 mm. 



Fig. 7. — Volutilithes petrosus Conrad. Jackson Race. Jackson, Miss. Adult 

 individual showing the general characters of the V. petrosus main stock. 

 The later whorls show the spiny stage. This is the culminant type of the 

 main stock. Length = 52 mm. 



Fig. 8. — Volutilithes petrosus Conrad. Bell's Landing Race. Bell's Landing, 

 Ala. Adult individual showing the slightly developed senile characters. 

 Length = .52 mm. 



Fig. 9. — Volutilithes petrosus Conrad. Wood's Bluff Race. Wood's Bluff, Ala. 

 Adult individual showing strongly developed senile characters. Length = 

 58 mm. 



Fig. 10. — Volutilithes petrosus Conrad. Hatchetigbee Bluff Race. Hatchetig- 

 bee Bluff, Ala. Adult individual showing extreme senility and dwarfed 

 size. This is the culminant type of the senile offshoot shown in figs. 8 and 

 9. Length = 43 mm. 



