A NEW GENUS AND NEW SPECIES OF ASELLOTE ISOPOD, CAECIJAERA HORVATHI, FROM LOS ANGELES-

The marine asellote fauna of California and especially of south-ern California is very poorly known. It is not surprising, there-fore, that several undescribed forms exist in the area. The spe-cies described herein is very remarkable for several reasons. It is found in association with the wood-boring isopod Limnoria sp. The Limnoria sp. of course has often been collected without the asellote; on the other hand, the fact that the asellote has not been collected outside of an association with Limnoria is suggestive that a close relationship exists between the two. Caecijaera is perhaps commensal with the wood-borer. The genus Iais [as represented by I. pubescens (Dana) ] contains exclusively commensal species which are associated with Sphae-roma and related genera. At least one species of Jaera is also occa-sionally found with sphaeromids (Arcangeli, 1934, pp. 1-19). In the case of Iais and Jaera the commensal asellotes are usually much smaller than the host, and in Iais, at least, the commensals freely traverse the dorsal and ventral surfaces of the sphaeromid or wander among the leaf-like pleopods, apparently undisturbed by the constant rhythmic motion of the pleopods. A similar relationship seems impossible in Caecijaera, because this pecies is often as large as medium-sized specimens of Limnoria. In Lim-noria sp. the size varies between 1.0 and 3.5 mm. i length an