562 TELEOSTEI chap. 



between the inner surface of the quadrate and a descending 

 process of the hyomandibular. Basis cranii double. Eibs 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. 



Fig. 340. — Side view of skull and pectoral- arch of Chirocentrus dorah. 



Chirocent7-us dorah, 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. Eibs 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 1 1 rays. Air-bladder 

 large, communicating with the ear. 



Four sub-families : — 



(i.) Theissopatrinae. — 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. 



