The hilt is a single piece casting of brass with 14 ribs between the pommel and crossguard.  The quillions are curved slightly forward with disk finials.  It has a bird's-head pattern pommel.  The straight double edged blade is diamond shaped in cross-section.  

Albert N. Hardin, The American Bayonet 1776/1964, #115, Type I

"The double-edged blade is 20.1875 inches (513 mm) long, 1.125 inches (29 mm) wide, and .1875 inch (4.8 mm) thick.  Both edges are "V" ground for their entire length and present a symmetrical diamond cross-section.  The blade profile is also symmetrical and terminates in a long tapering spear point.  There are no markings on the blade.

The light cast-brass hilt is 4.5 inches (114 mm) long.  The guard consists of short equal quillions of retangular cross-section cast integral with the grip which terminate in slightly forward-curving disk finials.  The pommel is of the bird's-head pattern but more rounded in profile than standard models.  A single transverse brass pin passes through the tang at the pommel.  A long flat locking spring fits into a recess milled along the upper flat of the grip.  The recess and spring continue around the heel of the pommel.  The spring is held by a round head screw just behind the guard.  The spring projects transversely out over the large rear locking bolster, where a steel pin welded vertically to the spring axis serves as a locking projection down into the bolster recess.  The rearmost portion of the spring is curved outward to provide a convenient grip.  A squared pin set into the pommel recess operates in a slot in the spring to limit its travel.  The only marking on the arm is a number stamped vertically in the obverse grip just behind the guard."    

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Russ Pritchard & John Ashworth, Confederate & Southern Agent Marked Shotguns, Page 306, provides great pictures of this bayonet showing details of the spring and lug extensions. 

"Cook & Brother sold bayonet components to the Memphis Ordnance Department.  The Memphis Novelty Works made all manner of brass castings.  Therefore, it is likely that blades for Type I (this bayonet) and Type II (Reference #412) are actually products of Cook & Brother."  Page 307

"The Memphis Novelty Works made all manner of brass castings and offered shotgun bayonets as proclaimed in their September 19, 1861 advertisement.  It is possible that the hilts of Types I (this bayonet) and III (Reference #413) were made by Memphis Novelty Works and blades attached were accured from Cook & Brother and other sub-contractors.  Based upon this theory, Types I and III are products of the Memphis Ordnance Department and later Briarfield Arsenal in Columbus, Mississippi"  Page 307