PYGMY SPERM WHALE PIERS. 105 



show, in a rather small area, just anterior to the pterygoids. The 

 pterygoids meet mesially for about half their length anteriorly, 

 then are separated by an elongate-ovate space, and again ap- 

 proximate posteriorly at their crests. Their posterior free 

 margins or crests are straight and set somewhat obliquely to a 

 transverse line. From the sides of the inferior nares, two sharp, 

 much elevated crests proceed backward, divergingly, to the 

 region of the auditory meatus, as is usual in allied animals. 



The interesting periotic and tympanic bones, or "ear-bones," 

 are dark coloured in the exterior member, which measures 5.8 

 cm. in vertical length, 3.4 cm. in antero-posterior breadth, and 

 2.1 cm. in greatest thickness at the superior end; while the 

 interior inflated, shell-like member (the tympanic) is ivory- 

 coloured, rather thin, and beautifully and rather intricately 

 convuluted in a manner which cannot be easily described. 

 Both of the ear-bones have been preserved and are com- 

 plete. The accompanying plate contains opposite sideviews 

 of the left ear-bone, on a scale slightly less than one- third 

 the natural size. As before mentioned, I believe the ear-bone 

 of this species has never before been figured. 



The mandibles (lower jaws) are very thin and delicate, 

 and have little depth at the anterior half where the tooth-row 

 is situated, but are moderately deep at the posterior ends. The 

 symphysis is long (6.5 cm.); and posterior to it the rami grad- 

 ually, and then strongly, separate from each other. The tooth- 

 rows are thus approximately parallel, and only 1 .5 cm. apart, 

 for about half the length of the rows. The length of the tooth- 

 row is contained in the mandibular length, 2\'2 times; the dis- 

 tance between the condyles is about ^, eths of the same length; 

 and the depth from the coronoid process to the angle, is con- 

 tained 2 %rd times in that length, while the depth at the tooth- 

 row is only 3^^th of the length of the tooth-row. 



Teeth. — Upper jaw toothless; teeth in lower jaw, 14 on each 

 side; dental formula, jfExj. The teeth are not very firmly 

 attached in the alveolae, and therefore may be slightly moved 

 about. They are rather small, slender, conical, decidedly 

 sharp, very slightly curved inward at the tip and also to- 

 ward the embedded basal part. Their total length, mid- 

 way in the row, is .73 inch; the diameter at the basal part is 

 .12 in., and the crown projects out of the gum .35 in. They are 

 separated, from centre to centre, .36 in. 



