A TWO-HEADED TORTOISE

A Two-headed Tortoise.

Seek Distances in Two-Headed Disk Systems

We make a correction to the calculation of mean seek time in a recent algorithm of intelligently positioned two headed disk systems. We also introduce a new two headed disk system with better mean seek time.

Inhibition of Regeneration in Two-Headed or Two-Tailed Planarians.

A two-headed reptile from the Cretaceous of China.

A malformed embryonic or neonate choristoderan reptile from the Lower Cretaceous Yixian Formation of northeastern China is described. The tiny skeleton exhibits two heads and two necks, with bifurcation at the level of the pectoral girdle. In a fossil, this is the first occurrence of the malformation known as axial bifurcation, which is well known in living reptiles.

A double-headed polyp

A 50-year-old man was seen as an outpatient for isolated, minimal and intermittent lower gastrointestinal bleeding. He had a history of well-controlled hypertension and diabetes. During his colonoscopy, a polyp with two heads that shared a common long and large stalk was encountered in the sigmoid colon (Fig. 1A). The heads were approximately 2 cm and 3 cm in size. Because of their overall size...