This chapter provides an overview of two specimens of a cestode from the spotted sting-ray (Aetobatis narinari) which are to be referred to the genus Tylocephalum. The specimen from the cow-nosed ray was a less mature strobile than than those from the spotted ray. The scolices were imbedded in the intestinal wall and had caused some ulceration. The chapter shows the general plan of arrangement of the genitalia. On the marginal sides of the testes are the vitelline glands which extend along each marginal border of the entire length of the proglottis, being interrupted only at the point where the cirrus pouch and the accompanying vagina approach the genital aperture. The uterus was represented by a tubular structure lying along the median line near one of the lateral faces of the proglottis, and extending from nearly one end of the proglottis to the other.