FISHES OF THE GENUS ACENTROPHORUS. 



29 



and grooves is indicated in text-fig. 3. On the side of the head 

 the sensory canals can be followed even more clearly. Three or 

 four pits are usually conspicuous in the length of the pre- 

 operculum, and from the lower end of this bone the line is con- 

 tinued by a groove across the angular, and by a chain of six or 

 seven well-marked pits along the dentary near its lower border 

 (text-figs. 5 and 6). finally, there are longitudinal grooves on 

 the inferior circumorbitals, probably marking the course of a 

 suborbital canal. 



The pectoral girdle is rarely seen at all completely, being 

 largely covered as a rule by the operculars and branchiostegal 

 rays. Its general shape, however, can often be seen thi'ough 

 these bones (text-figs. 7 and 14), and more or less of the thickened 

 portion of the cleithrum (" clavicle "), ornamented by fine trans- 

 verse raised lines, appears normally along the lower edge of the 



Text-fiffure 8. 



Outline restoration of shoulder-girdle of Acentrophorus varians. A., right side, 

 external view ; B., left side, internal view. Double dotted line shows course 

 of lateral line. cL, cleithrum; p.tm., post-temporal; s.c.c, position of 

 scapulo-coracoid cartilage ; s.cl., supraclavicle. About three times natural 

 size. 



suboperculum. Occasional specimens show some portion of the 

 girdle more fully, especially from the inner side, and make 

 possible such a restoration as is given in text-fig. 8. The large 

 scale-like post-temporal has already been i-eferred to. The supra- 

 clavicle, which normally appears in part behind the operculum, is 

 of simple, slightly curved form, strengthened along its anterior 

 edge. The cleithrum is massively thickened externally in a 

 boomerang form, pointed at either end, and with a band of fine 

 transverse raised lines marking the portion which sometimes 

 appears at the surface below the suboperculum. Its inner fa,ce 

 is expanded and flattened, especially about the middle of its 

 length, but this face also bears a rod-like thickening, bent almost 



