Cetacea toothed whales and two in baleen whales. The nostrils are located on top of the head above the eyes so that the rest of the body can remain submerged while surfacing for air. The back of the skull is significantly shortened and deformed. By shifting the nostrils to the top of the head, the nasal passages extend perpendicularly through the skull. The teeth or baleen in the upper jaw sit exclusively on the maxilla. The braincase is concentrated through the nasal passage to the front and is correspondingly higher, with individual cranial bones that overlap. In toothed whales, connective tissue
Flat-spired three-toothed snail among 40 species of tridopsine snails in eastern North America. Populations were divided into family trees showing the phylogenetic relationships among 18 groups of species. Nine of these groups consisted of a single species, of which "Triodopsis platysayoides" was one group. This species of snail is endemic to the United States. The flat-spired three-toothed snail is found only in West Virginia, among Upper Connoquenessing sandstone outcroppings and boulders, in a restricted area along the rim of the Cheat River gorge. The U.S. Fish and Wildlife Service considers this snail to be threatened since 1978. Little is known about the life