6 
Oliver and Salisbury . — On the Structure and 
Text-fig. i. Diagrammatic sketch of a median longitudinal section of Conostoma oblongum upon 
which are plotted the approximate positions of the planes of section of all preparations used in this 
paper. The reference letters and numbers given with each section on the figure are the designations 
under which the preparations are cited in the explanation to the plates. R = University College 
Collection; W = Mr. D. M. S. Watson’s Collection. 
