This bayonet has a typical Collins style short hilt.  The smooth ribbed brass hilt is 118 mm long and has 15 ribs.  The muzzle ring is flush to the hilt flat and the inside diameter is 22.9 mm.  The only example recorded has a two digit number stamped horizontally on the hilt flat between the muzzle ring and lug slot in a 1 mm font. There is a forward swept round finial on the bottom of the guard and no finial on top of the muzzle ring.  The press stud and 51 mm long spring are typical Collins construction.  The center of the cross guard has a steel rivet through the blade.   

The lug slot is chamfered around the top edge and there is a 23.5 mm guide slot.  There appears to be a insert into the lug slot to shorten the slot length several millimeters.  

The yataghan blade is ~510 mm long and has unstopped fullers.  The only example recorded is marked COLLINS & CO / HARTFORD / 1861 in three straight lines on the left ricasso .  It is unusual to find the logo and date on the same side of the blade.