Presence of from four to five sharp cusps or tubercles on the crown of the molars.
Inclined forwards; canines, upper small or moderate, conical I or o and sharp-pointed; lower absent or rudimentary; premolars variable; molars 3, or 2 i with four obtuse tubercles, sometimes.
There is also the Moloch horridus of South and Western Australia, covered with tubercles bearing large spines, which give it a very strange aspect.
40); in Geryonia, however, it remains double, and the centripetal canals arise by parting of the two layers; (4) excretory endoderm, lining pores at the margin of the umbrella, occurring in certain Leptomedusae as socalled " marginal tubercles," opening, on the one hand, into the ring-canal and, on the other hand, to the exterior by " marginal funnels," which debouch into the sub-umbral cavity above the velum.
In some Leptomedusae excretory " marginal tubercles " are developed on the ring-canal.
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