1910.] AXATOMY OF THE FRILLED SHARK. 563 



The basipterygium is a stout cartilage, articulating b} r means 

 of . a comparatively small surface with the postero-lateral border 

 of the pelvic girdle. It has a rounded dorsal edge, is somewhat 

 laterally compressed, and is also outwardly curved, Garman (10) 

 says that at its extremity it has a series of three radials. These 

 would seem to correspond with the distal segmented portion of the 

 basipterygium and the two attached radials which I have figured; 

 That the proximal one of these parts is a portion of the basi- 

 pterygium is obvious from the figure (19), It carries, moreover, 

 the penultimate radial. 



Garman's figures (Pis. xi. & xii.) are scarcely to be trusted; 

 as the two which he gives of these cartilages are different from 

 each other in many respects, and particularly in regard to the 

 points in question. There is, it must be admitted, a certain 

 amount of variability in these cartilages, for in the fin of the 

 opposite side to the one figured the basipterygium is bisegmental 

 distally and the attachment of the terminal radial is slightly 

 different. Moreover, there are differences between the one 

 figured here and those given by Goodrich (13) in his plate of 

 figures illustrating Ghlamydoselachvs. 



The lateral radials are attached to the ventro-lateral edge of 

 the pelvic girdle and of the basipterygium. They are for the 

 most part trisegmental, whilst those at the anterior end are 

 somewhat irregular in outline and show signs of fusion in some 

 of their parts. The proximal segments of those attached to the 

 pelvic girdle are dorsally flattened and are directed outward, 

 obliquely downward, and slightly posteriorly. The median and 

 distal segments of these lie more in the horizontal plane and are 

 more rounded than the proximal segments. The radials attached 

 to the basipterygium are, on the whole, narrower than those 

 attached to the girdle, and they gradually become more attenuated 

 as we proceed posteriorly. The last one is bisegmental and the 

 three before that are complete. 



The extraordinary length of the flattened pelvic girdle, the 

 correspondingly large number of attached lateral radials, and 

 the large number of latei'al nerve foramina afford strong evidence 

 of the primitive nature of the pelvic girdle in Chlamydoselachus. 



VIII, The; Mixipterygia (Copulatory Appendages or Claspers). 

 (Plate XLYI. figs. 20-22.) 



j. Measurements. 



ins. cms. 



Length of animal 52 1 30 



,, girdle -f appendage ,, 8'5 21 "4 



,, appendage 4'5 1 1 "25 



,, free part of appendage.., 1*9 4'8 



Maximum width of appendage 0'6 T4 



,, „ across, fins 5 12'5 



Length of basipterygium B' ,, 1-5 3 -8 



,, axial cartilage & 45 11-6 



36* 



