. The sea-beach at ebb-tide : a guide to the study of the seaweeds and the lower animal life found between tidemarks . e carapace, above the are divided so as to present much surface to the water, fromwhich they absorb oxygen. They are like a dense mass of littletubes arranged along a central tube. The class has two kinds ofeyes, simple and compound; the latter are composed of a number ofe\es. In some species the eyes are placed on the ends of mova-ble stalks, which enable the creature to see in all directions andfrom a higher plane than the body occupies. As a rule, the eye
. The sea-beach at ebb-tide : a guide to the study of the seaweeds and the lower animal life found between tidemarks . e carapace, above the are divided so as to present much surface to the water, fromwhich they absorb oxygen. They are like a dense mass of littletubes arranged along a central tube. The class has two kinds ofeyes, simple and compound; the latter are composed of a number ofe\es. In some species the eyes are placed on the ends of mova-ble stalks, which enable the creature to see in all directions andfrom a higher plane than the body occupies. As a rule, the eyesoccur in the head region, but in the shrimp I^n/tlKinsin they are onthe thorax and abdomen. In barnacles simple eyes exist in theyoung stage,but in adult forms there are no apparent visual ear (so called) consists of a sac containing small siliciousparticles suspended in fluid. Numerous fine hairs on the innersurface of the sac, connect, with nerve fibrils. The organs of hearing are in various places. In decapods, orthe larger CwistuccK, they are at the base of the autennules. 248 MARINE INVERTEBRATES. Zoea of Cancer irroratus. Last stagebefore it changes to the megalops con-dition. The muscles are white bundles of fibers, and are in strips,which is an indication of power and activity. There are fourimportant sets: twisted ventral muscles which bend the tail andare particularly large and strong, those which straighten the tail, those moving the appendages, andthose which work the gastric mill. The eggs, after being discharged,are attached to the abdominal legs ofthe mother by a kind of cement, orthey are carried in pouches attachedto the thorax. In these positions theymature, and hatch at different stagesof development in different emerge with three pairs of legs,and are known as Nauplius; some areZoea, having a carapace and abdominalsegments, but no abdominal appendages. Another stage is Megalops,with large stalked eyes. Others are hatched as miniature
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectmarinea, bookyear1901
