PLATE XLII. 



Heteroceras Hornbyense (page 332). 



Figure 1. One of the two original and dextral types of this species, 

 shewing only the spirally coiled portion of the shell. 



Figure 2. Part of the spirally coiled portion of a sinistral specimen, 

 the type of H. perversum. 



Figure 3. Spirally coiled portion of another sinistral specimen. 



Figure 4. The largest specimen known to the writer, shewing part of 

 the spirally coiled portion, and the free, deflected an I 

 abruptly bent or hook-shaped part of the shell, as des- 

 cribed on page 333. 

 All the specimens figured on this plate are from Hornby 

 Island. 



