Two new marine sponges, Clathria(Clthria) gimnyeoungenesis n. sp. and Clathria(Clthria) reticularis n. sp., were collected in Jejudo Island, Korea by fishing nets in September 1994. C.(C.) gimnyeoungenesis n. sp. is closely related to C.(C.) toxipraedita Topsent, 1913 based on spicule types, but are different in the size of spicules and growth forms. Especially, the thick styles and large toxas length of this species are half of C.(C.) toxipraedita. Growth form of the new species is branched but massive encrusting in C.(C.) toxipraedita. C.(C.) reticularis n. sp. is similar to C.(C.) compressa Schmidt, 1862 based on spicule types, but are different in the size of spicules. Especially, large toxas of this new species is twice as long as C.(C.) compressa and they have large isochelae, which are absent in the latter.