528 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 
to the following conclusion: there are in the Philippine Islands, and 
in the adjacent regions to the northward and southward, three geo- 
graphical subspecies which apparently intergrade in the two regions 
where their ranges meet. The typical striatissimus, originally de- 
scribed from Japan, ranges southward to China, Formosa, and the 
east coast of Luzon. It intergrades off the northwest coast of Luzon | 
with the subspecies torvus, which inhabits the Sulu Sea and the China 
Sea off southern Luzon. The form torvvus then intergrades, along the 
Tawi Tawi Archipelago, with the third subspecies, aegev, which in- 
habits the East Indian Islands south of the Philippines. 
The diagnostic characters, in so far as we have been able to analyze 
them, seem to be but three or four in number: 
1. The ventral rays in striatissimus and aeger are 8 in number, 
~ while in torvus, which occupies a region between the other two forms, 
there are 7. 
2. The orbit is nearly circular and very large in striatissimus, but 
smaller and more obliquely elongate in torvus and aeger. 
3. The barbel is usually longer than the pupil in the southern 
form aeger, about as long as the pupil in the typical striatissimus 
and usually shorter than the pupil in the central subspecies, torvus. 
4. The color may average darkest in forvus, but the character is 
not constant and is not very valuable in distinguishing the sub- 
species. 
It will be noted that the intergrades between striatissimus and 
torvus have the eight ventral rays of the former, but usually have 
the small and less regular orbit and the short barbel of torwus. The 
intergrades between forvus and aeger likewise usually have eight 
ventral rays, and have the small irregular orbit as in both forvus 
and aeger. It follows from these facts that the two sets of inter- 
grades are difficult to distinguish from one another, although the 
three typical forms may readily be separated. The chief average 
difference between the intergrades seems to be in the length of the 
barbel, which averages greater in the specimens from the Tawi Tawi 
group than in those from off northwest Luzon. 
Tables showing the diagnostic characters of the subspecies of Hymenocephalus 
striatissimus and of the intergrades between these subspecies. 
= VENTRAL RAYS.! 
Species. | 6 7 8 9 
P | | 
StriqhissiMUs 22. ccc ous sees See en eee oe Se eee ee Ret aaa eine ae ee eee See biaeeee | 70 2 
Intergrades q,. 7.2: See tee os ae oe 2 a ee te eae re a cares [eee eee 2 | ee oss 2-02 
LOTVUS .cn.0= 2 = eL OSE = Cee ee eC ae Sa eee © cron, Se eros eereiee nate | 4 302) 4 scces os cos eae eee 
Intergrades's2). Sage. 5 woes sien Salle lao ee ae EEE oe fs ROSS SLES 30 | 111 | sce es 
MEGET Sr as cain cn ace om saat ae aoe eae cease ciate oie arelisiote Cetera ameter 2 125: Ago see 
| 
!‘ Number of fins, not specimens, are enumerated; the number is often not the same on the two sides 0 
the same fish. 
? Japanese material included; the types, not here listed, also have 8 ventral rays. 
