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 have been 

 erased from these figures since they do not 

 agree with present-day practice. 



The first critical description of the 

 lateral line and head-canal system of 

 Chlamydoselachus is that given by Mrs. 

 Hawkes (1906, p. 960-964) in connection 

 with her work on the cranial and spinal 

 nerves of this fish. She has renamed the 

 head-canals on the basis of their innerva- 

 tion, using the method now generally em- 

 ployed by comparative anatomists. 



The latest and best-illustrated work on 

 the lateral line system and associated organs 



Text-figure 20 

 The sensory canals and pores on the head of 

 Chlamydoselachus: A, in lateral; B, in dorsal view. 

 The letters designating the canals and pores in the 

 original figure have been erased since in the main 

 they do not agree with present-day nomenclature. 

 For the modern terminology see Allis in Text-figure 

 21, and Figure 7, plate II. 

 After Garman, 1888. 



