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POFULAR SCIENCE REVIEW. 
some degree from those which have been described. Each of 
them consists of a short stem bearing a single calycle, clearly the 
equivalent of the ordinary pinna (PL CX., fig. 7 p), and between 
the front of this calycle and the sarco theca which usually 
adheres closely to it, rises a tall recurved appendage, bearing 
along one edge a line of “calicetti,” which give it the appearance 
of being serrated like a saw (PI. CX., fig. 7 a). These secondary 
appendages bend inwards, their extremities crossing above, and 
constitute the protective portions of the corbula. The exact 
significance of these structures I cannot determine ; they do 
not take the place of the anterior sarcotheca, which is present as 
usual, but spring, as I have already stated, from the stem sup- 
porting the calycle between the latter and the sarcotheca ; and as 
in some cases after reaching a certain height they give origin to 
a second calycle (PI. CX., fig. 7 c'), bearing a similar appendage 
similarly placed, they must, I think, be regarded as of the 
nature of ramules , though abnormally developed. But into 
such detail I do not propose to enter here. I merely wish to 
direct attention to the developmental history of the corbula 
as fully unfolded to us in the series of existing specific forms. 
I have thus endeavoured, with as little use of technical 
phraseology as possible, to indicate the chief characteristics of 
the Plumularian family, the most significant points in its 
history, and the leading traits of its remarkable beauty. I 
have only to suggest in closing that those who seek rest and 
health at this season by the seaside may readily find some 
members of the tribe that I have attempted to sketch, amongst 
the waifs on the beach or in the charming nooks and corners of 
the tidal pools, and may study them at first-hand with much 
delight and profit to themselves. 
DESCRIPTION OF THE PLATES. 
PLATE CX. 
Fig. 1. Aglaophenia tubulifera, Hincks, of the natural size. 
„ 2. Tlumularia Catharinci , Johnston, of the natural size. 
„ S. Aglaophenia pennatula, Ellis and Solander, natural size. 
„ 4. The corbula of Aglaophenia pluma , Linnaeus, magnified, a. 
The mid-rib. b , b. Lateral appendages, c. One of the re- 
productive capsules. 
„ 5. Portion of a plumule of an Australian species, bearing modified 
pinnae, a , a. Normal pinnae, with calycles. b , b. Modified 
pinnae, with sarcothecae, but without calycles, supporting 
reproductive capsules. 
