REPORT OF THE DIRECTOR I9II I33 



ever, at the base of the fin, three small elements, parallel to one 

 another, which are articulated proximally with one or two elements 

 that can not be clearly made out on account of their crushed con- 

 dition. These two rows of cartilaginous elements correspond 

 respectively with the a-2 and a-3 series of the pelvic fin figured by 

 Goodrich.^ 



Regarding the supports of the unpaired fins, those of the second 

 dorsal (D-) and of the anal (A) are beautifully shown. Their 

 number, form and arrangement are already well known from Whit- 

 eaves's restoration. They are almost exact counterparts of each 

 other. One point worth noting is that in the anal there seem to be 

 only two instead of the three separate basilar rods found in the 

 dorsal. The internal supports of the first dorsal (D^) are also to 

 some extent shown, although one can not make out the separate 

 parts beyond what they are shown in the figure. 



A feature of great interest in the specimen is the clearness with 

 which the vertebral centra (V) are shown in the front half of the 

 fish. The presence of vertebrae in Eusthenopteron has already been 

 recorded by Traquair.- They extend only as far back as the 

 first dorsal, behind which the notochord was apparently continuous, 

 although neural and haemal spines were well developed. Twenty 

 centra can be counted between the cleithrum (CI) and the first dorsal 

 fin. They are seen in profile so that one can not be certain whether 

 they are complete rings or not. Each is about two and one-half 

 times as high as wide, and provided with a neural spine. The haemal 

 spines, if present in this region, are not shown. The centra are 

 separated from one another by narrow spaces which increase back- 

 ward until, near the end of the series, they are equal to the width 

 of the vertebrae. 



MEASUREMENTS OF THE SPECIMEM 



Total length 2 feet 10 inches 



Total length, allowing for missing tip of the tail 2 " 11 " 



Head (to end of operculum) 7^ " 



Depth across head (i inch back of eye) 3^ ," 



Depth in region of D^ 4^ " 



Depth between D^ and anal 4 " 



Gular plate, length (slightly restored) 5^ " 



Gular plate, greatest width i5^ " 



Greatest height of caudal fin 6^)4 " 



1 Goodrich, E. S. On the Pelvic Girdle and Fin of Eusthenopteron. Quart. 

 Jour. Microscop. Sci., N. S., XLV, p. 311-24, pi. xvi. 



2 Op. cit. p. 17. 



