A NEW WHALEBONE WHALE 45 RjDEWOOD, W. G

1922. Observations

on

the skull in foetal specimens ofwhales of the genera Megaptera

and

Balaenoptera. Philos. Trans. Roy.

Soc, London,

ser. B, vol. 211, pp. 209-272, 16

figs.

May

8,1922.

ToBiN,

William

_J.,

and

T.

Dale Stewart

1952. Gross osteopathology.

American

Acad, of Orthopaedic Surg. Instructional Course Lectures,

Ann

Arbor, vol. _9, pp. 401-411, 14 figs.

True, Frederick W.

1904.

The whalebone

whalesofthe western

North

Atlantic,

compared

with those occurring in

European

waters with

some

observations

on

the species of the

North

Pacific.

Smithsonian Contr. Knowl., vol. 33, publ. 1414, pp. vii.+331, 97 figs., 50 pis.

June

^1904.

1912.

The

genera of fossil

whalebone

whales allied to Balaenoptera. Smithsonian Misc.

Coll., vol. 59,no. 6, publ. 2081, pp. 1-8. April 3, 1912.

Turner, William

1913.

The

right

whale

of the

North

Atlantic, Balaena biscayensis; its skeleton described

and compared

with that of the

Greenland

right whale, Balaena mysticetus. Trans. Roy.

Soc. Edinburgh, vol. 48, no. 33, pp. 889-922, figs. 16-25, 3 ^pis.

Van Beneden,

P. J.

1886. Description des ossements fossiles des environs d'Anvers. Part 5. Genres: Amphicetus, Heterocetus, Mesocetus, Idiocetus

&

^Isocetus.

Ann. Mus.

Hist. Nat. Belgique, Bruxelles, vol. 13, ^pis. 1-75.

Walmsley, Robert

1938.

Some

observations

on

thevascular systemofa female fetal finback. Contr.

Embryol.

Carnegie Inst, of Washington, Publ. 496, no. 164, pp. 107-178, 27 figs., 5 pis.

May

31, 1938.

Winge, Herluf

1910.

Om

Plesiocetus

og Sqvalodon

lira

Danmark.

Vidensk.

Medd.

Naturh. Foren. i

Kj0ben-

havn

for 1909, pp. 1-38, 2 ^pis.

2. The Miocene ^Calvert Sperm Whale

Orycterocetus

A

SINGULAR SORT OF

REMODELING

of the skull led to the separation of the physeteroid stock

from

other odon- tocetes which, with the exception of the ziphioids,

seem

to

have

followed a

more

conventional line of

development

in cranial architecture.

As

earlyasthelowerMiocene,

sperm

whales

were

differentiated

by

these cranial modifications

from

the

main

odontocete stocks.

On

the skulls of

two

lower

Miocene

genera {Diaphorocetus

and

Idiorophus), the adipose cushion, or reservoir for spermaceti,

had

spread

backward

behind the nasal passages

and

the consequential adjustmentofinvolved cranialbones

formed

asupracranial basin.

The

"dishing-in" of the roof of the braincase is

attributableinpart, atleast, tothe pressure ofthisdevelop- ing spermaceti reservoir.

The accompanying

alterations oftherelativeproportions

and

relationsofthe dorsal cranial bones included the depression of the frontal bones along the

median

longitudinal line, the posterior enlargement or widening ofthe upturned right premaxillary, the crestlike elevation of the maxillaries laterally, the loss or

marked

reduction of

one

of the nasalbones

and

the flattening of the other against the frontal behind the greatly enlarged left nasal passage,

and

the

marked

widening of the rostrum proximally.

Some

genera of extinct physeteroids retain afunctional dentitionin the

upper

jawstothecloseoftheir

known

geologicalhistory.

Other

generaexhibit atendency for the teethto

become

loosely implanted in large alveoli, while the intervening septa diminish in thickness

and

ul- timately disappear, leaving

an open

alveolar gutter in the maxillary {Aulophyseter).

Teeth were

lodged in distinct alveoli ineach maxillaryofthisCalvert

Miocene

Orycterocetus.

Owen

seemsto

have

been the first torecognize the phy- seteroidaffinitiesofaTertiaryfossiltooth,

and

consequently Balaenodon

(Owen,

1846, p. 536, figs. 226-229)

became

the

first generic

name

to be applied to a fossil

sperm

whale.

The

typeof Balaenodonphysaloides

Owen

comprises aportion of the root of a tooth

from

the

Red Crag

of Felixstowe, Suffolk, England.

Abel

(1905, p. 52) concludedthatwith-

out

doubt

thistooth belonged to the physeteroid Scaldicetus caretli, butthatthebasis forvalidation of thescientific

name was

insufficient.

The

type tooth, however, is considerably larger

and

structurally different

from

the teeth of Orycterocetus.

The

nextoldest available

name

fora fossil

sperm whale

is Hoplocetus Gervais (1849, p. 161, pi. 20, figs. 10-11) based

on two

teethfoundinthemiddle

Miocene

shellmarl(faluns) in the vicinity of

Romans, Department Drome,

France.

The two

type teeth ofHoplocetus crassidens (typespecies) are characterized

by

an enlarged or swollen root setoff

from

a proportionately small

crown by

a necklike constriction.

Abel

(1905, p. 53) rejects the validityof the stated generic characters of Hoplocetus, but nevertheless places it in the

synonymy

ofScaldicetus.

The

pulp cavity is closed on

one

of these teeth

and

reduced toavestige

on

the other.

The

teeth ofScaldicetus caretti aside

from

their larger di- mensions are characterized

by

having the

enamel on

the

crowm

verycoarse

and

rugose, the ridgesanastomosing but generally running

toward apex

of

crown

with

numerous

connectingor intersectingstriae;

no

perceptible constriction of the root atbaseofcrown.

Inasmuch

as the

above-mentioned

extinct physeteroids cannot conceivably

have any

bearing

on

the generic alloca- tion of the Calvert

Miocene sperm

whale,

no

fiirther con- sideration is given to their status.

ORYCTEROCETUS Leidy

Orycterocetus Leidy, Proc. Acad. Nat. Sci. Philadelphia, vol. 6 (1852-53),p. 378,August 1853.

Type

Species: Orycterocetus quadratidensLeidy.

Diagnosis:

Twenty

teethineach

upper jaw

(17 of

which were

lodged in alveoli in maxillary

and

3 present

on

pre- maxillary). Dentine core of slender curved teeth often with

open

funnellike pulp cavity; fine annular lines of

47

48 UNITED STATES NATIONAL MUSEUM BULLETIN

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