Journal of morphology . channel,hollowed out in the cartilaginous capsule. These canals are by 1 The position of this organ is shown in PL I, Fig. 3, ab. and rl. ab. No. I.] THE VERTEBRATE EAR. 13 no means semicircular in shape, nor are they placed at rightangles to each other. The planes in which the canals for the most part He are notparallel with the three planes of the animals body; viz. thesagittal, transverse, and horizontal respectively. The extent of the variations from these three planes are shownin Cuts 2-6. The anterior vertical canal ca., as seen from above,bends caudad in its dist
Journal of morphology . channel,hollowed out in the cartilaginous capsule. These canals are by 1 The position of this organ is shown in PL I, Fig. 3, ab. and rl. ab. No. I.] THE VERTEBRATE EAR. 13 no means semicircular in shape, nor are they placed at rightangles to each other. The planes in which the canals for the most part He are notparallel with the three planes of the animals body; viz. thesagittal, transverse, and horizontal respectively. The extent of the variations from these three planes are shownin Cuts 2-6. The anterior vertical canal ca., as seen from above,bends caudad in its distal portion, and cephalad in its proximalportion ; its plane cuts the sagittal plane of the body at anangle of 50°. The angle included between it and its fellow, theposterior vertical canal icp), is not 90°, but only 82°. The angleat which the posterior vertical canal cuts the sagittal axis ofthe body is consequently 48°, and it does not coincide with anytransverse plane passed through the body. It is thus seen that. Cut 2. — A projection of the semicircular canals of the ear of the Torpedo occi-dentalis on the horizontal plane, to show their angular relations to the vertical(sagittal) plane. the vertical canals do not lie in planes parallel with two axialplanes of the body, respectively, the sagittal and the transverse,as is commonly supposed. The so-called horizontal canal, or, asI prefer to designate it, the external, does not lie in a planeparallel with the horizontal plane of the body, but always, as Ihave found it, inclined in two directions to that plane. Theusual arrangement is presented by the Torpedo where the planeof this canal inclines downwards and forwards from the hori-zontal. On comparing the various canal-forms found among verte-brates, one is struck by the great variety presented. The 14 AYERS. [Vol. VI. size, the shape, the position of the parts of the canalar archwith respect to the tliree planes of space are subject to exten-sive variation. We have jus
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Keywords: ., bookauthorwistarin, bookcentury1800, bookdecade1890, bookyear1892
