562 TELEOSTEIL CHAP. 
between the inner surface of the quadrate and a descending 
process of the hyomandibular. Basis cranii double. Ribs very 
slender, sessile, very low down on the centra ; no parapophyses ; 
epipleurals and epineurals. Pectorals inserted very low down. 
Post-temporal forked; postclavicle absent; a thin bony lamina, 
similar to the postclavicle, above the pectoral fin, attached to 
the scapula; scapular foramen in scapula; coracoids in contact 
with each other, forming a keel. Ventrals very small, with 7 
rays. Brachiostegal rays 8. Air-bladder large, not communi- 
cating with the ear, incompletely divided into cells. Mucous 
membrane of the intestine forming a spiral fold. 
The body is very elongate and strongly compressed, covered 
with thin, deciduous scales; the vertebrae number 75. The 
dorsal fin is short and opposite to the anal, which is long. 
Fic. 340.—Side view of skull and pectoral arch of Chirocentrus dorab. 
Chirocentrus dorab, the only representative of this family, 
inhabits the Indian Ocean and the seas of China and Japan. 
Fam. 16. Clupeidae—Margin of the upper jaw formed by 
the praemaxillaries and the maxillaries. Supraoccipital separat- 
ing the small parietals; opercular bones well developed. Basis 
cranii double. Ribs mostly sessile, inserted behind parapophyses ; 
intermuscular bones (epineurals, epipleurals, adpleurals) usually 
numerous. Post-temporal forked, the upper branch attached to 
the epiotic, the lower to the opisthotic ; post-clavicle applied to 
outer side of clavicle. Ventrals with 6 to 11 rays. Air-bladder 
large, communicating with the ear. 
Four sub-familes :— 
(i.) THRISSOPATRINAE.—Mouth large; praemaxillaries very 
small; maxillaries large, with rather narrow supplemental bone, 
firmly attached to praemaxillaries; branchiostegals about 30; 
abdomen compressed to an edge, without serration; no lateral 
line. Thrissopater, from the Gault of Folkestone. 
