A TWO-TENTACLED, COMMENSAL HYDROID FROM CALIFORNIA (LIMNOMEDUSAE, PROBOSCIDACTYLA)

Abstract

A new unnamed hydroid. Proboscidactvla sp., found living as a commensal upon the tubes of the sabellid polvchaete. Pseudopo-tamilla ocellata. is descr., with discussion of each of the obvious types of individuals found in the colony, gastrozooids and gonozooids, as well as a descr. of the immature free medusa and the nematocysts of the hydroid and medusoid phases. The relationships of the hydroid to the worm are discussed, especially the utilization by the hydroid of the feeding currents produced by the worm. The history of the Proboscidactylidae, a family name here used for the first time, is summarized, and changes are suggested in the definition of the family. The new hydroid is compared with other proboscidactylans, and it is concluded that this hydroid may possibly be that of the medusa. P. occidentalis. The relation of Proboscidactvla to Monobrachium parasitum is discussed.