NOTES ON A PORPOISE FROM THE HAWAIIAN ISLANDS. 
813 
The number of valid species of the genus Prodelphinus is at present uncertain. 
In 1889, after an examination of the types of many of the nominal species and 
numerous other specimens belonging to the genus, I arrived at the conclusion that 
about eight species were probably distinct;® of these, the one to which the Hawaiian 
specimens should most probably be assigned is Prodelphinus attenuatus (Gray), of 
which P. capensis (Gray) is, I believe, a synonym. 
A comparison of the dimensions of the type skulls of these two species with 
those of the Hawaiian skulls and Dr. Abbott’s Indian Ocean specimens is given in 
the following table, the various dimensions being reduced to percentages of the total 
length. 
Measurement. 
g 
Type of P. attenua- 
tus. 
U.S.N.M. 112832, 
Hawaii. 
U.S.N.M. 112833, 
Hawaii. 
U.S.N.M. 36050 9, 
Amirantes Islands. 
U.S.N.M. 36049 <?, 
Amirantes Islands. 
U.S.N.M. 36051 ?. 
Providence Island. 
U.S.N.M. 36031 9, 
Alphonse Island. 
1 U.S.N.M. 36048 rf, 
Johanna Island. 
mm. 
mm. 
mm. 
mm. 
mm. 
mm. 
mm. 
mm 
Total length 
413 
383 
422 
443 
415 
407 
403 
397 
379 
p. ct. 
p.ct. 
p. ct. 
p. ct. 
p. ct. 
p. Ct. I 
p. ct. 
p. ct. 
Length of beak 
Breadth of beak at base of maxillary 
60.8 
62.6 
60.7 
60.9 
61.7 
60.8 
60.7 
58.6 
notches 
22.8 
22.7 
22.9 
20.8 
22.9 
23.3 
22.6 
24.2 
23.8 
Breadth of beak at its middle 
10 
10 
11.4 
10.4 
10.1 
10.6 
10.2 
10.8 
10 
Breadth of intermaxillae at middle of beak . 
Greatest breadth between outer margins 
5.8 
5.2 
5.2 
5 
5.8 
6. 1 
. 5.7 
'6.5 
6.1 
of intermaxillse proximally 
16.2 
15.9 
16.6 
15.8 
15.9 
16.4 
16.1 
17.6 
16.9 
Length of superior tooth line 
51.8 
50.2 
53.3 
52.4 
53 
52.1 
53.3 
52.6 
50.4 
Last tooth to base of maxillary notch 
Extremity of beak to anterior margin of 
10.4 
11.2 
10.7 
10.2 
10.6 
11 
9.4 
10.6 
9.8,7 
superior nares 
70.7 
68.4 
71.8 
72.5 
71.1 
72.5 
71.4 
70.3 
67.5 
Breadth between orbits 
Breadth between hind margins of tem- 
39.7 
38.4 
37.7 
37 
38.1 
38.3 
38.7 
39.3 
38.5 
poral fossae 
30.8 
30 
29.4 
29.4 
31.2 
30.3 
31 
30.9 
Length of temporal fossae 
16] 2 
17 
14 
14 
14.5 
16 
15.9 
16.4 
16.6 
Depth of temporal fossae 
13.6 
13.1 
11.6 
a 11. 3 
11.3 
13.2 
13.2 
14.1 
14.2 
Length of mandible 
84.7 
85.9 
86.2 
84.6 
84.4 
85.2 
84.8 
| 82.4 
83.4 
Length of symphysis of mandible 
Length of tooth row of mandible 
18.6 
19.3 
17.5 
17.4 
19.3 
18 
18,4 
17 
17. 1 
50 
50.4 
50 
50.8 
50.4 
50.4 
51.6 
50 
49.1 
Depth between angle and coronoid process. 
13.8 
13.8 
14 
12.9 
13.4 
15.6 
14.6 
15.6 
14 
/40-41 
43-43 
44^3 
42-43 
38-38 
38-38 
39-39 
44-43 
41-39 
138-37 
42-42 
42-40 
39^0 
36458 
38-37 
39-39 
40-41 
39-40 
nil. 5 per cent if measured on continuation of raised posterior border: this is on the right side. On the left the 
depth is 9.5 per cent, or, if measured on continuation of posterior border, 10.6 per cent. 
The correspondence of proportions in these several skulls is remarkable. Sir 
William H. Flower, no less than myself, was of the opinion that P. attenuatus and 
P. capensis are specifically identical. I have already advanced the view that Dr. 
Abbott’s Indian Ocean specimens also belong to that species, 6 and would now 
assign the Hawaiian skulls to the same. It will be observed that in the Hawaiian 
skulls the temporal fossae are smaller than in the type of P. attenuatus or that of 
P. capensis. This might be regarded as of some importance were it not that two 
skulls from off the Amirantes Islands (Nos. 36049 and 36050 U.S.N.M.), which 
there is every reason for believing belong to the same species, show an exactly parallel 
variation as compared with each other. 
a Bull. TJ. S. Nat. Mus., 36, 1889, pp. 61-75, 162-166. 
&Proe. U. S. Nat. Mus., 17, 1894, paper No. 982. 
