376 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 
along eastern Luzon. The East Indian species Lionurus evides is 
closely related only to LZ. condylura of Japan. 
Only 11 species were obtained about the Sulu or Tawi Tawi Archi- 
pelago, which separates the East Indian and the Philippine sub- 
regions: 7 are found in the subregions on both sides, while 3 species * 
were not dredged elsewhere; the Lymenocephalus striatissimus of 
the Tawi Tawi region is intermediate between the East Indian //. s. 
aeger and the Philippine ZZ. s. torvus, but nearest /7. s. aeger. 
B. THE PHILIPPINE SUBREGION. 
This subregion includes the waters about the central Philippine 
Islands, north of the Tawi Tawi group, and south of west-central 
Luzon, and exclusive of the Pacific Ocean along the east coast of 
Luzon. While sharing many of its species with the East Indies, 
this subregion is inhabited by a number of peculiar and often singular 
forms: Bathygadus sulcatus; Gadomus magnifilis; Coryphaenoides 
semiscaber (representing the East Indian (. tydeman) ; three species 
of Coryphaenoides, each known only from its type dredged in the 
depths of the Jolo (Sulu) Sea—namely, (. paradoxus, C. dubius, and 
C. camarus; Coelorhynchus quincunciatus® and thompsoni, C. veli- 
fer, C. macrolepis, C. carinifer, C. acutirostris; Hymenocephalus 
gracilis (closely related to the Hawaiian H. tenuis); H. longiceps; 
IT. s. torvus (representing /7/. s. striatissimus of Japan, Formosa, and 
eastern Luzon, and //. s. aeger of the East Indies; intergrading with 
striatissimus off northern and northwestern Luzon, and with aeger 
about the Tawi Tawi group) ; Malacocephalus luzonensis®; Ventri- 
fossa macronemus (most nearly related to V. misakia of Japan and 
eastern Luzon) ; Ventrifossa lucifer; Lionurus decimalis. 
The Philippine subregion appears to lack certain species of the East 
Indies, as the A/batross failed to obtain them during months of in- 
tensive dredging within the limits of the subregion. These species 
follow: Bathygadus filamentosus, B. entomelas, Gadomus multifilis, 
Coryphaenoides asprellus, C. tydemani, C. heyningeni, C. aequatoris, 
C. orthogrammus, C. sp. Weber, Coelorhynchus platorhynchus and 
acantholepis, Hymenocephalus s. aeger, H. grimaldti, Malacocephalus 
2 laevis, Lionurus infranudis, L. evides, L. vittatus, L. richardi, and 
L. parvipes, Mataeocephatus adustus, Cetonurus robustus. 
In contemplating such a peculiar fauna occupying a comparatively 
restricted area, one is led to examine the hydrographic data of the 
region to determine whether the physical conditions of life may be 
obviously unusual. Such an examination does, in fact, indicate that 
the basic conditions of depth and temperature throughout this sub- 
region are in peculiar relationship to each other. Briefly stated, the 
1The closely related Coelorhynchus serradiatus, C. notatus, C. triocellatus. 
2 One specimen also dredged off eastern Luzon. 
