EASTMAN: STKUCTUKE AND KELATIONS OF MYLOSTOMA. 29 



nately not preserved for its entire length, but would seem to have heen 

 at least 15.5 cm. long, exclusive of its terminal process. The dimensions 

 of the ventro-lateral plates cannot bo determined with any great nicety, 

 but although exhibiting about the same proportions, they are fully one- 

 fifth smaller than the corresponding elements in the uniciue example of 

 Mylostoma fig\u-ed by Dean. 



