. The Bashford Dean memorial volume : archaic fishes. Fishes; Sharks; Fishes, Fossil. The ?iatural History of the Frilled Sharif 289 III) the lateral line is beautifully clear and distinct. On the right side we find marked sinu' osities on the "small" of the tail, and on the left are like sinuosities directly opposite. Whether other sharks show such variations in the position of the lateral lines, we cannot say. At any rate we have never found them. Study of our specimens of Chlamy- doselachus seems to indicate that variations of position are most likely to occur on the "small&q
. The Bashford Dean memorial volume : archaic fishes. Fishes; Sharks; Fishes, Fossil. The ?iatural History of the Frilled Sharif 289 III) the lateral line is beautifully clear and distinct. On the right side we find marked sinu' osities on the "small" of the tail, and on the left are like sinuosities directly opposite. Whether other sharks show such variations in the position of the lateral lines, we cannot say. At any rate we have never found them. Study of our specimens of Chlamy- doselachus seems to indicate that variations of position are most likely to occur on the "small" of the tail. This is in confirmation of Carman's and Mrs. Hawkes' observations. These sinuosities of the lateral line in the tail-section of Chlamydoselachus are well por- trayed in Ito's colored figure (our Text-figure 5). Possibly these variations may be taken as indications of the plasticity of this lowly shark. Following her remarks on these varia- tions, Mrs. Hawkes pertinently states: The conclusion arrived at from these facts is that the lateral Line system of Chlaynydo' selachus is primitive as regards (1) the open condition of a portion of the canals; (2) the cutaneous rather than subcutaneous position of the canals; (3) the entire absence of tubules in many places. In the occipital and hyomandibular regions, however, the system tends to a con- siderable complexity. Again there are indica- tions, in the occipital and lateral canals, of either a vestigial or rudimentary complexity. Canals, Pores and Pit Organs on Head.—On the head of Chlamydoselachus are found many branches of the lateral line system, some open and some closed. These were first figured and described for Chlamy- doselachus by Carman (1888) in the general paper on the lateral line system in Elasmo- branchs above referred to. Carman's figures showing the distribution of these are repro- duced herein as our Text-figure 20. The letters giving Carman's designations of these canals, pores and pit-organs
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