170
WILLIAM MACNAE
FIG. 52. Heaps of mud thrown up by Thalassina anomala in a ceriops zone. (Drawn
from a colour transparency taken between Mossman and Port Douglas, March
1962.) (From Macnae, 1966.)
FIG. 53. Sesarma srnithii. The spines on the finger of the cheliped are diagnostic of this
species. I n many species of Sesarma a row of nodules occurs along this ridge of the
dactyl, and by scraping these ridges together sound is produced. The pattern of
nodules and hairs on the pterygostomial region is diagnostic of the genus and is
used in reoxygenating water pumped up out from the gill cavity t o which the
water returns. (ca. nat. size.)