Pethia tiantian Pethia tiantian Pethia tiantian is a species of cyprinid fish that has only been recorded from streams in the vicinity of Putao in the far north of Myanmar. It grows to a length of SL. It is generally brownish with a dark vertical bar just behind the operculum and a round dark blotch on the caudal peduncle. Other "Pethia" species are similarly marked but "P. tiantian" can be distinguished by its longer lateral line, reaching all the way back to the base of the caudal fin. "P. didi", a similarly marked species found in the same drainage basin, differs from
Operculum (gastropod) to push into the substrate in a leaping form of locomotion. Virtually all pulmonate snails are inoperculate, i.e. they do not have an operculum, with the exception of the Amphiboloidea. However, some terrestrial pulmonate species are capable of secreting an epiphragm, a temporary structure that can in some cases serve some of the same functions as an operculum. The epiphragm may be distinguished from the true operculum by its homogeneity and want of growth marks. In ammonites (extinct shelled cephalopods), a calcareous structure known as the aptychus (plural aptychi) existed. When these were first described they were thought to be