429 



measured 5,25 inches in length. The second piece which also posses- 

 sed a fin structure was attached above the foregoing, was directed 

 obliquely forward and upward and measured about 2,5 inches. The 

 third part was 3,5 inches long, irregular in form, had a slight curv- 

 ature, and projected vertically upward. The whole was covered with 

 unmodified integument (Fig. 1). 



Fig. 1. Specimen No. 1, rshowing accessory fins structures as seen in fresh specimen 



On removal of the skin it was seen that the accessory structure 

 consisted of two fin-like portions articulated to a "girdle" of peculiar 

 appearance. This last piece was firmly attached by one end to the 

 anterior vertebral plate, covering an area of about an inch in width 

 and half an inch in length, and lay almost entirely on the right side 

 of the middle line. The median ridge of the vertebral plate was in 

 consequence bent towards the left side, and on removal of the piece 

 in question it was seen to have been inserted into three well defined 

 depressions on the upper surface of the plate. There was a small 

 amount of free movement backwards and forwards; the protractor 

 scapulae of the right side was in part interrupted , the portion 

 nearest the middle line being inserted by a strong aponeurosis into 

 the base of this "girdle", posteriorly, and into its forwardly directed 

 face, anteriorly. This muscle on the left side was quite normal. The 

 effect of this arrangement would be a loss of muscular power in 

 elevating the head region on the right side unless compensated by the 

 stronger development of other muscles, e. g. the levator rostri, 

 right. This, however, was symmetrical with the left. The distortion 

 seen in the vertebral ridge did not extend to the neural canal, the 

 central nervous system was unaffected, and all other parts were present 

 and quite normal, as far as could be made out. 



The "girdle" consists of five distinct pieces of cartilage (Fig. 2). 

 In appearance it is quite unlike either the pectoral or the pelvic girdle 

 of the skate and its homology — if it may be regarded as having 



