380 



Bashford Dean Memorial Volume 



THE ANAL FIN 



In the endoskeleton of the anal fin of Chlamydoselachus (Text'figures 48 and 52 

 after Garman and Deinega respectively) there is some fusion of proximal elements, and 

 even a slight amount of fusion of distal elements. The elements of the basal series are 

 usually oriented in a different direction from the distal elements. In the adult, this 

 fin skeleton is very long and slender (in an anteroposterior direction). The same is true 

 of the anal fin skeleton of a 225'mm. embryo figured by Osburn, 1907 (Fig. 6, pi. IV). 

 In this embryonic specimen the fusion of basal elements is not so pronounced. The separa- 

 tion of the fin skeleton from the vertebral column is very marked. In Heptanchus cinereus 

 (Daniel, 1934, Fig. 57 after Mivart) there is a fairly large basal element in series with 

 some smaller basal elements, all apparently formed by the fusion of radials. 



Text 'figure 52. 

 Endoskeleton of the anal fin of Chlamydoselachus anguineus (showing basals 1-20). 



After Deinega, 1909, Fig. 13, pi. IV. 



THE CAUDAL FIN 



The general appearance of the cartilaginous supports for the dorsal and ventral 

 lobes of the greater part of the tail fin is shown in Deinega's (1909 and 1923) Fig. 9, pi. Ill, 

 which is too large for satisfactory reproduction here; also in Carman's (1885.2) PI. 14, 

 which was drawn from a specimen in which the tip of the tail had been mutilated during 

 life. Details are better shown in Goodey's (1910.1) drawings reproduced herein as 

 Text-figures 31 and 36. 



The cartilaginous supports for the ventral lobe of the caudal fin of Chlamydosela' 

 chus are suppHed almost entirely by the haemal spines, which belong to the axial skeleton. 

 The occurrence of small radials distinct from the haemal spines is confined to the anterior 

 portion (Text-figures 31 and 48) of the ventral lobe, and these radials are possibly seg- 

 mented off from the haemal spines. 



The cartilaginous supports for the dorsal lobe of the caudal fin of Chlamydoselachus 

 consist partly of neural spines, which belong to the axial skeleton; but there is an entire 

 series of dorsal radial elements (Text-figures 31 and 36) distal to the neural spines. 

 'Tor a short distance in front . . . the series is separated by a space from the neural 



