J. K. TharJier — Median and Paired Fins. 287 



Second Dorsal of Mvstelus cams, PI. L and LI, figs, ll-lf). 



Fig. 11 has 24 rays. fig. 12 has 22. fig. 13 has 2:i, fig. 14 has 24, fig. 15 has 24. Tluis of 

 the five examined three have 24, one 23 and one 22 rays. It seems probable that a 

 wider examination would give as forms having 25 or more rarely 2(). Thus we have 

 for the second dorsal 24 rays with some slight variation. 



Extra segmentations appear only in fig. 11, ray 5 ; and fig. 14, ray 2. Tliis gives -0 + . 



I estimate the concrescence at -06. The concrescence is mostly confined to tlie 

 proximal row, and is more frequent at the two ends than in the middle of the series. 



Betipping is seen only in fig. 14, ray 23. This gives ^0 + . 



Ratio of proximal piece of middle ray to middle piece '6. 



Ratio of distal piece of middle ray to middle piece -4. 



Tlie downward prolongation of the proximal parts of one or two of the orad ra^-s is 

 noticeable, being quite pronounced in all the cases except that represented in fig. 1 1 . 



The reduction of the rays is rare, but shown to an extreme extent in fig. 11, ray 1 ; 

 and fig. 15, ray 1. 



Anal of Mustelus canis, PI. LI and LII, figs. 16-19. 



Figs. 16 and 17 have each 18 rays. Fig. 18 has IT or 18 according as the last ray 

 is double or not. Fig. 19 has 18 or 19 under the same conditions. The great width 

 of the last ray in the last two cases makes the larger number probable. Thus we 

 have 18 as the normal number, with probably slight variations. 



Extra segmentations are seen in fig. 17, ray 5 ; and fig. 19, ray 3. This gives '0 + . 



The concrescence I estimate at -09. Betipping occurs in fig. 16, ray 3. This gives "0 + . 



Ratio of proximal piece of middle ray to middle piece is -I. 



Ratio of distal piece of middle ray to middle piece is "6. 



First Dorsal of Galeocerdo tigrinus, PI. LII, fig. 20. 



In this sole specimen there are 25 rays. 



Extra segmentation occurs in 10, 20, 21. 22, 23, which gives -2. It should be 

 noticed that this extra segmentation is in each case here a doubling of the proximal 

 line of segmentations. 



Concrescence is estimated at -06. Betipping is seen in 18, 19 and 25. This gives '1. 



Ratio of proximal piece of middle ray to middle piece 1-1. 



Ratio of distal piece of middle ray to middle piece -6. 



Shortening is seen in 6 and 22. In the latter the proximal piece is ext luded from 

 the edge of the fin by a, the proximal piece of 2;!, and by the proximal piece of 21. 

 The piece a consists of two lateral halves. 



Second Dorsal of Galeocerdo tigrinus, PL LII, fig. 21. 

 Number of rays 13. Extra .segmentation in 3, giving -1. 

 Concrescence is estimated at -01. Betipping, in 5, 8 and 13, gives -2. 

 Ratio of proximal piece of middle ray to middle piece 1-3. 

 Ratio of distal piece of middle ray to middle piece -6. 



Anal of Galeocerdo tigrinVjS, PI. LII, fig. 22. 

 Number of rays 12. Extra segmentation in 6, 7. 8 and 10. gives 3. 

 Concrescence is estimated at -05. Betipping in 4 gives "l. 

 Ratio of proximal piece of middle ray to middle piece I'l. 

 Ratio of distal piece of middle ray to middle piece -7. 



