314 SIDNEY F. HARMKR. 



thickeniug, wliicli runs along each margin of the branch. 

 The retractor muscles of the polypide originate from the two 

 lateral walls. On each side there is a strong fan-sliaped 

 group passing to the base of the tentacles, and another 

 passing to the junction of the pliarynx with the oesophagus. 



Onchoporella bombycina, Bnsk^ (not Ell. and Sol.). 



Although I have had only dry material of this species to 

 work with, I can state that there is a well-developed com- 

 pensation-sac, opening by the crescentic median pore, the 

 tongue-like lobe to which the crescentic shape i.s- due being 

 distal, and seeming to be a triangular membrane which curves 

 into the distal border of the compensation-sac (as in fig. CO). 

 The operculum is of very delicate texture. On eitlier side of 

 the orifice, somewhat proximally, there is a short spine, on 

 the proximal side of which is a pore, which is either a simple 

 funnel-shaped deficiency of the calcareous wall, or it consists 

 of tAvo, or even three, funnel-shaped tubes contained in a 

 single longitudinal groove. A similar ai-rangement is shown 

 in fig. 60 (/.). One or two pores of the same kind may 

 continue the line of this groove down the fi-ontal surface of 

 the zooecium. 



The branches have a calcareous mai-ginal thickening, which 

 may have a zigzag course; it is composed of numei-ous small 

 pieces, an arrangement which clearly gives a certain amount 

 of flexibility to the frond. 



Microporella malusii,- vVud. (fig. 03). 



The median pore {m. p.) has a distal concavity, due to the 

 projection into it of a tongue-like })rocess which is partly 

 membranous. Between this and the straight base-line of the 

 semicircular operculum is a triangular group of pores, the 



' Busk (1S52), )). 52. Tlic species dcscrilied hy Ellis and Solamier (' Nat. 

 Hist. Zoopli.,' 178C), |). 14), i'lom the Baliania Islands, appears to be a 

 Eu thy lis. 



» llincks (1880), p. 211. 



