The sternum of _bairdii_ (Pl. 32, fig. 2) consists of five segments and
does not offer characters by which to distinguish it from that of
_arnuxii_. In the former species the first eight pairs of ribs possess
distinct heads and tubercles; the tubercle is rudimentary in the ninth
pair and absent in the tenth and eleventh.
The dimensions of the three skeletons of _bairdii_ and of that of
_arnuxii_ described by Flower are as follows:
_Dimensions of one skeleton of Berardius arnuxii and three skeletons of
B. bairdii._
Column Headings:
_B. arnuxii._
B: New Brighton, New Zealand, 1868, (Flower). No. 3.
_B. bairdii._
C: 49726 St. George Island, Alaska, female adult.
D: 49725 Centerville, California, male(?) adult.
E: 49727 St. George Island, Alaska, male young.
B C D E
mm. mm. mm. mm.
Length of centra of seven cervicals 254 375 310 250
(inferior)
Atlas:
Breadth 292 362 341 280
Height ... 339 321 270
Fourth cervical:
Greatest height ... [a]254 [a]249 [a]191
Greatest breadth ... [b]243 [b]197 [b]173
Length of centrum 36 47 34 30
Seventh cervical:
Greatest height ... 310 270 198
Greatest breadth 241 257 235 177
Length of centrum 46 58 49 42
First thoracic:
Greatest height ... 391 390 255
Greatest breadth ... 310 290 240
Length of centrum 58 84 68 51
Ninth thoracic:
Greatest height ... 508 478 333
Greatest breadth ... 318 [c]218 198
Length of centrum 152 190 176 128
First lumbar:
Greatest height ... 585 540 359
Greatest breadth ... 626 575 340
Length of centrum 163 228 215 150
Sixth lumbar:
Greatest height ... 713 642 427
Greatest breadth ... 590 572 362
Length of centrum 206 273 243 172
First caudal:
Greatest height ... 800 [d]658 427
Greatest breadth ... 577 [d]511 360
Length of centrum 246 338 [d]280 200
Ninth caudal:
Greatest height ... 422 335 288
Greatest breadth ... 243 194 191
Length of centrum 168 241 194 160
Eleventh caudal, length of centrum 104 180 156 142
Length of scapula 503 710 670 395
Height of scapula 356 490 445 280
Length of humerus 274 ... 340 248
Breadth of humerus at distal end 109 ... 170 115
Length of radius 295 ... [a]380 220
Breadth of radius at distal end 84 ... 140 88
Length of ulna (incl. olecranon) 323 ... ... 241
Breadth of ulna at distal end 79 ... ... 71
Length of sternum 1,143 1,455 1,530 ...
Breadth of first segment of sternum 325 375 495 ...
Length of first rib (straight) 457 543 505 323
Length of fifth rib (straight) 991 ... ... ...
Length of tenth rib (straight) 737 ... ... ...
[a] Median.
[b] Inferior.
[c] Process aborted on one side.
[d] Second.
Genus HYPEROÖDON Lacépède.
HYPEROÖDON AMPULLATUS (Forster).
_Balæna ampullatus_ Forster, Kalm’s Linnean Travels, vol. 1, 1770, p.
18, footnote.
_Balæna rostrata_ Müller, Zool. Dan. Prodrom., 1776, p. 7.
_Hyperoödon butskopf_ Lacépède, Hist. Nat. des Cétacés, 1803-4, pp.
XLIV and 319.
_Hyperoödon rostratum_ Wesmael, Nouv. Mém. Acad. Roy. Bruxelles, vol.
12, 1840, pls. 1, 2.
_Hyperoödon ampullatus_ Rhoads, Science, new ser., vol. 15, 1902, p.
756.
The National Museum has one skeleton of this well-known species, somewhat
imperfect, which is labeled as having been obtained on the coast of
Norway, and was received about the year 1875. Its catalogue number is
14499. This skeleton is about 19 feet long and has the following
vertebral formula: C. 7; Th. 9; L. 9; Ca. 19 (+1?) = 44 (or 45). Eight
chevrons are attached to the caudal vertebræ, and at least two more were
present originally. The fifth thoracic vertebra has no facet on the
centrum for the head of the sixth rib, but the latter articulates with a
small facet on the side of the centrum of the sixth thoracic vertebra.
The seventh thoracic has a well-developed transverse process on the side
of the centrum. The ninth rib is shorter and more slender than the
others. None of the transverse processes of the caudal vertebræ are
perforated by foramina. These processes end on the eighth caudal, and the
neural spines on the tenth caudal. The free ends of the neural spines of
the thoracic and lumbar vertebræ are all more or less rounded. The
pectoral limbs are incomplete.
So far as I am aware, only three examples of _Hyperoödon_ have been taken
on the coasts of the United States, as mentioned in the list on page 2.
The skeleton of one of these (from North Dennis, Massachusetts) is in the
Museum of Comparative Zoology, Cambridge, Massachusetts, and the skull of
the second (from Newport, Rhode Island), which was a female, is in the
Academy of Natural Sciences of Philadelphia.[62] This skull is
represented in Pl. 32, fig. 3.