. Annual report. New York State Museum; Science; Science. FOURTH REPORT OF THE DIRECTOR I907 ' 159 illustrations of a worm from the Hamilton group described by Hall as Spirorbis angulatus from closely attached examples showing but one or two entirely horizontal volutions. These silica etchings show how quickly in later growth the tube departs from the horizontal position and draws out into a loose spiral even when not confronted by the necessity of keeping its feeding end on a level with that of some companion organism [pi. 2, fig. 8-11]. The third of these combinations is illustrated by a spe
. Annual report. New York State Museum; Science; Science. FOURTH REPORT OF THE DIRECTOR I907 ' 159 illustrations of a worm from the Hamilton group described by Hall as Spirorbis angulatus from closely attached examples showing but one or two entirely horizontal volutions. These silica etchings show how quickly in later growth the tube departs from the horizontal position and draws out into a loose spiral even when not confronted by the necessity of keeping its feeding end on a level with that of some companion organism [pi. 2, fig. 8-11]. The third of these combinations is illustrated by a specimen for which I am again indebted to Professor Calvin. A little colony of Favosites has had its tentacular surface entirely overgrown with a Stromatopora. Within the substance of the Stromatopora is a multitude of spiral worm tubes not stretched out into loose volu- tions as in the other instances mentioned, but keeping their two or three volutions in close contact and resembling an Autodetus with- out its external smoothly sloping surface. The edges of these tubes are apparently always angular. These little worms have started growth anywhere on the substance of the Stromatopora and instead of growing like a Spirorbis with whorls broadly attached for a turn or two, have coiled closely upward and ceased growth in every case very abruptly. This case is singularly in- structive as showing that the worm failed to keep pace in growth with the coral and confessed its natural limitations of growth, while in the other cases cited the worm apparently has had the ability to adapt itself to this upward growth by stretching out its tube into loose curves and keeping its aperture always clear at the surface. The little Streptindytes compactus however was not equal to this struggle for existence except as it planted its successors in- d. ^z/E&f Stromatopora with embedded spiral annelid tubes. Streptindytes compactus, located at various stages of the growth of the coral. The character o
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