Lectures on the comparative anatomy and physiology of the invertebrate animals : delivered at the Royal College of Surgeons . is of opinion thatthe pouches situated in the confluent segments beneath the freepart of the outer maxillae are olfactory; their orifices areproduced or tubular in many Barnacles, but not in the sessileCirripeds. Although the eyes of the Cirripeds are more or less aborted intheir mature state, they retain sufficient susceptibility of light toexcite, in the pedunculated species, when a shadow passes overthem, retraction of the cirri, and, in the sessile species, a sudden
Lectures on the comparative anatomy and physiology of the invertebrate animals : delivered at the Royal College of Surgeons . is of opinion thatthe pouches situated in the confluent segments beneath the freepart of the outer maxillae are olfactory; their orifices areproduced or tubular in many Barnacles, but not in the sessileCirripeds. Although the eyes of the Cirripeds are more or less aborted intheir mature state, they retain sufficient susceptibility of light toexcite, in the pedunculated species, when a shadow passes overthem, retraction of the cirri, and, in the sessile species, a suddenshutting of their opercules; the same act is caused by the sound orvibration of an approaching footstep ; it indicates that they appre-ciate the atmospheric movements produced by the approximation ofthe hand, even, according to Dr. Coldstream, when it is not broughtnearer the shells than twelve or fourteen * CCXXIV. p. 88. t lb. p. 95. X CCXVI. p. 688. 282 LECTURE XIII. The marine animalcules brought to the mouth {^fig. 124, a\ by thecurrents of the cirrigerous feet (6), and seized by the lateral jaws, are 124. Lepas. conveyed by a short oesophagus, having a bell-shaped expansion of thelining membrane, to a dilated stomach (<?), which is of unusual lengthin Tubicinella, From six to eight c^eca are developed from the upperpart of the stomach, in several species of Balanus, and are branchedin Bal. perforatus. They are not developed in Tuhicinella. Theintestine {d) is bent upon the stomach, and tapers with a slightlysinuous course to terminate at {d\ the base of the caudal appendage {e).The intestinal canal is lined by a chitinous epithelial tube, which iscontinued above into the cseca. Darwin has observed it to be ex-pelled entire, with the excrement, in a living Balanus; it has beendeemed analogous to the typhlosole in the earth-worms intestine.* The stomach is coated by small, opaque, pulpy, branched glands,probably subserving a hepatic function: these are arranged
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Keywords: ., bookauthorowenrichard18041892, bookcentury1800, bookdecade1850
