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Bashford Dean Memonal Volume 



infundibulum, bu: m rhe higher vertebrates it disappears from the basis cranii during 

 later development. 



In connection Vv-ith his account of the persistence of the notochord of Chlamy- 

 doselachus in the region of the basis cranii, Goodey (1910.1, p. 543) makes the following 

 interesting statement: "The cartilage of the floor of the cranium in the region of its 

 junction with the vertebral column is thick and somewhat hea\Tly calcified. It here 

 shows some indications of its probable vertebral nature, by the sHght resemblance which 

 the calcmcarion presents to the inverted V-formation found in the centra of the vertebral 

 column." Avers ' lSS9j found more decided evidences (my Text-figures 21 and 22) of 



Test-figure 21. Test-figure 22. 



Sections through the skull of the frilled shark, Chlamydoselachus anguineus. 



Text-figure 21. A transection of the basis cranii near the vertebral articulation, to show the fig- 

 ure made by the calcareous sheath (and its processes) of the notochord, resembling a vertebra of 



the trunk region. 



cent., ver te bral centnim (sheath rf notochord); di., chc^da dorsalis; cranxsv., cxanial cavity; ct., cartilage of the basis cranii; 



n.j>., neural {gorrs^; tj-.p., transverse process. 

 After Ayers, 1889, Fig. 8. 



Text-figure 22. Left half of the hemisected cranium, to show the relations of the notochord and 

 cranial aorta to the basis cranii and to the pituitary prominence and space. 



c, cranial aorta; du, chorda doialis (notochcxd); ir., iotemal carotid artery; \., cephalic aorta; p.pl., pituitary plexus; pt., 



pituitary space; tr.c, transverse canal; III, third pair of aortic arches. 



After Avers, 1889, Fig. 3. 



the persistence of the notochord (ch) and the rudimentary vertebral column in the basis 

 cranii of his specimen; but in view of the doubts that have been expressed concerning 

 the accuracy of many of Ayers' obser\7ations on Chlamydoselachus, one should accept 

 this description and the accompanying figures with some reserve. In Hexa-iichus the 

 notochord Text-figure 23, nc) persists in the posterior portion of the basis cranii, much 

 as in ChJ.d-'nydoselachus. 



My Figure 4, plate II, shov.Tng a medial view of the cranium of Chlamydoselachus, 

 should be compared with Text-figure 23, shouTing a similar view of the cranium of Hexan- 

 chus. The t^-o figures are of interest chiefly because they show the foramina for the 

 exit of the cranial and occipital nerve roots. 



