Actiniae. 299 



endodermal muscles are feeble, supported by short simple outgrowths 

 of the mesoglcea, and contrast greatly with those of U. stdcata. 



Brood Cliamliers. — The adult females possess brood chambers 

 similar in position and appearance to those of U. sulcata, except that 

 the contained embryos do not form such distinct prominences on 

 the body-wall, nor are there any instances where the oral disc, 

 tentacles and upper third of the column have sunk by contraction 

 below the level of the top of the brood chambers. One individual 

 has been preserved in a very interesting stage, showing one of the 

 embryos partly out of the brood chamber, and two others visible from 

 the outside, the opening to the chamber extending round almost half 

 of the circumference of the column (figs. 18 and 19). Each individual 

 in this species usually contained six embryos. 



Halntat. — Dredged from a gravelly bottom in 20-28 fathoms of 

 water, off Cape Adare, South Victoria Land. 



Several of the specimens dissected had a single specimen of a 

 species of Amphipoda among the retracted tentacles, apparently 

 commensal. My friend Mr. Alfred 0. Walker, to whom I submitted 

 it, informs me it is a new species of Jassa — J. goniamerus. 



The Appearance and Structure of the Brood Chambers 

 distinct from the ccelenteron. 



In the year 1869 Professor Verrill (6 p. 490-492) described in 

 two species of Actinia {Phellia ardica, Verrill, and E'piactis prolifera, 

 Verrill) from the Arctic seas, a series of well-defined pits scattered 

 over the surface of the body-wall, in which the eggs are retained 

 until hatched, when the young embryos are provided with tentacles. 

 Later, in 1899, he described some additional species (7, V. p. 375) 

 belonging to the Bnnodactidm, also possessing these peculiar pits, 

 and gives figures. Each pit is formed by a hollow in the mesoglcea 

 into which the ectoderm is invaginated. 



In 1893 Dr. Carlgren published a preliminary announcement, 

 "iirber das Vorkommen von Brutraumen bei Aktinien" (1 p. 231). 

 Here he described two types of brood chamber: (1) when the 

 ccelenteron itself acts as such — a condition of things which 

 obtains in some British species; and (2) the formation of pit-like 

 depressions generally scattered on the lower part of the column. 

 These latter apparently are similar structures to those described by 

 Verrill in 1869 and 1899. But Carlgren goes on to describe how 



