As the varieties here mentioned are very remarkable, and may perhaps turn out to be true species, I think they are worth describing in some detail: I will only further add, that we must either make several new species, or consider, as I have done, several forms as mere varieties. C. VIRGATA, var. CHELONOPHILUS of _Leach_. Pl. III, fig. 2 _c_. Atlantic Ocean, 35° 15´ N., 16° 32´ W. On the Testudo caretta. Capitulum not above half an inch long, composed of very thin membrane, with six bands (as stated by Leach) of faint colour; summit bluntly pointed; valves very small, far distant from each other; the scuta are imperfectly calcified, the central part of the umbo consisting of thick, brown chitine, with imbedded shelly beads; terga and carina perfectly calcified. _Scuta_ trilobed, flat, within slightly concave, upper lobe rather more acuminated than the lower; lateral lobe triangular in outline, twice as wide as either the upper or lower lobes; lying in the same plane with them and standing out at almost exactly right angle. _Terga_, flat; placed obliquely to the scuta, and barely half as long; separated from them by nearly twice their own length; upper and lower points acuminated; the umbo on the carinal margin forms a projecting shoulder; the scutal margin is straight, they are separated by nearly their own length from the apex of the carina. _Carina_ narrow, very slightly arched, within slightly concave, both points acuminated; lower third rather wider than the upper part; in length equalling three fourths of the scuta, and longer by one third than the terga; about as wide as the latter. _Filaments, Cirri, and Mouth_ exactly as before. In some specimens sent to me by the Rev. R. T. Lowe from off the _Testudo caretta_, taken near Madeira, the scuta have their lateral lobes broad and nearly rectangular: the carina extends nearly to between the terga: the terga are nearly straight, somewhat pointed at both ends, distant from the scuta, almost solid within, with their upper points bowed outwards: the whole capitulum is bluntly pointed, as in the _var. chenophilus_, to which form this makes a rather near approach. C. VIRGATA, var. OLFERSII. CINERAS OLFERSII. _Leach._ Tuckey’s Congo Expedition. _Hab._ South Atlantic Ocean. _Scuta_, unlike on the opposite sides of the same individual, on one side with a single lateral lobe as usual, but this very narrow, on the other (fig. 2 _d_), with five lobes or projections. _Terga_ slightly concave within, separated by a little more than their own length from the tips of the scuta, and by one third of their own length from the tip of the carina. _Carina_ longer than the scuta by about one fifth or one sixth of its own length, blunt at both ends, considerably bowed.