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spots that seemed to be especially attractive were beds of old, 

 vigorous plants of Posidonia growing in sheltered pools (at 

 low water), with a coarse sand or shell-grit bottom. The 

 Steno chitons were usually about 3 inches deep in the shell grit, 

 buried in the brown sheaths of Posidonia, but in a few cases 

 odd specimens were found on the bases of the leaves outside the 

 sand. Until recently most of the specimens that have been 

 collected were these odd ones that had not worked their way 

 down in the grit. The species hereunder described under the 

 name of S. posidonia! is also lives on the same plant, Posidonia 

 australis, and I have found it in every locality I have visited 

 in this State where this plant is growing. It is almost always 

 found on the white or near the white bases of the leaves, just 

 above the sand, and does not seem to bury itself in it. The 

 best way to obtain it is to pull up bunches of Posidonia from as 

 low down as possible, and search the white bases of the leaves 

 for the Stenochiton. If held up to the sunlight they are easily 

 perceived, even when on the reverse side of the leaf. The 

 species hereinafter described as Stenochiton cyniodocealis is 

 found on the cylindrical stems of the marine plant Cymodocea 

 Antarctica, which belongs to the same order as the preceding. 

 I am indebted to Mr. F. L. Saunders for pointing out this 

 plant to me, he having on a previous occasion taken this 

 Stenochiton at Normanville on this plant, but had wrongly 

 identified it as Stenochiton pollens, Ashby. I was able to obtain 

 a nice series at that locality, and on searching the same plant 

 afterwards at Cape Jervis, Encounter Bay, and still more 

 recently at Marino, I have been able to find it at all these 

 localities. The favourite spots seem to be the sheltered or 

 shore side of beds of Vymodocea, growing in situations more 

 or less sheltered. They are to be found usually only an inch 

 or two above the point where the plant stems enter the sand. 

 In no case have I found them on the short, flat leaves of this 

 plant. The girdle of this Stenochiton is in nature strongly 

 incurved, almost reaching right round the cylindrical stems of 

 the plant. The fourth species, Stenochiton pollens, Ashby, has 

 up to the present only been found by dredging, and the plant 

 it lives upon has not, therefore, been identified. 



Colour protection. — There is surely some connection 

 between the habits of these four species and the markings and 

 colouration that is peculiar to them. S. juloides is dark 

 brown in colour, of the same tone as the brown sheath of 

 Posidonia. S. posidonia is normally yellowish-green, and 

 shell is very transparent, so that it blends remarkably well 

 with the leaf it is on. It is nearly always found on the basal 

 portions of the leaf that are either very pale green or whitish. 

 The markings are suggestive of dashes of darker green on the 



