8 • PROCEEDINGS OF THE NATIONAL MUSEUM. vol.66 



Whale — that is, they are decidedly more constricted at middle in 

 proportion to their len2:th than in the Blue Whale, 



Pelvic 7mdiments. — No pelvic rudiments were preserved. 



Hyoid hones (pi. 18, figs. 2 and 3), — Though the material for com- 

 parison is not sufficient to give positive results, it indicates that the 

 hyoid bones of the Pollack Whale dilfer noticeably from those of 

 the other finbacks in the great depth of the concavity on the dorsal 

 side of the combined basihyal and thyrohyals (fig. 3). In the 

 Florida specimen the depth of this concavity is 225 mm. and the dis- 

 tance between the inner margins of the tips of the thyrohyals is 685 

 mm. The depth of the concavity is therefore 32.8 per cent of the 

 width. In a hj^oid of the Blue Whale from Newfoundland (No. 

 237567) the same measurements are, respectively, 275 and 1310. Here 

 the depth of the concavity is only 20.9 per cent of the width. Yet 

 the hyoids of this Blue Whale and of the mounted specimen (No. 

 49757) appear to be distinctly more concave than in the mounted 

 specimens of the Common Finback (No. 16045) and Pike "Wliale 

 (No. 20931). The thyrohyals in the Pollack ^Vliale are much longer 

 relatively to the central mass of the bone than in the Pike Whale, 

 and they are not expanded at the middle as in the two specimens of 

 the Blue Y»niale. The photograph does not give a projjer idea of the 

 size and length of the thyrohyals in the Florida specimen. It shows 

 the bone from the ventral side with the thyrohyals curving away 

 from the camera and consequently much reduced in apparent size 

 as compared with the central portion of the bony mass. The same 

 is true of the figure published by Andrews (fig. 13, p. 356). I can 

 see no important features in the stylohyal (fig. 2). 



Tyiiipanic and peiiotic hones (pi. 22). — The smaller auditory 

 bones have been lost. Probably they were jarred out of place during 

 the period when the skeleton was being carried about the country 

 on a truck. The tympanic and periotic of the left side are shown in 

 several aspects on plate 22. Material for comparison with the ear 

 bones of other finbacks is not very satisfactory, owing to the absence 

 of fully authenticated specimens of Sihhaldus^ but there appear to 

 be rather well-marked characters by which the various Atlantic 

 species of baleen whales can be identified on the basis of the periotic 

 bone. 



The periotic of Euhakena (family Balmnidoi) is immediately dis- 

 tinguishable from that of the finbacks and humpback (family 

 Balainoptendce) by the relative positions of the anterior and poster- 

 ior petrous processes. The anterior process in Euhakena is drawn 

 inward toward the posterior process, so that the axes of the two pro- 

 cesses converge at an angle which is decidedly less than a right angle 

 instead of somewhat greater than a right angle as in the finbacks 

 and humpback. Apparently this difference is due almost entirely 



