FISHERY BULLETIN: VOL. 73, NO. 3 



Table 13.-Number of pectoral rays in species of Sardini. 



Species 



21 



22 23 24 25 26 27 28 



N 



1) 



anterodorsal end on postcleithrum 1, which is 

 unique among bonitos. Postcleithrum 1 in Or- 

 cynopsis and Cybiosarda is elongate and broad at 

 the upper end. The general features of 

 postcleithrum 1 of Sarda species are similar to 

 those of Thunnus. Allothunnus has the broadest 

 postcleithrum 1. Postcleithrum 2 (the lower one) is 

 a spinelike structure with both ends pointed and a 

 broad upper process (Figure 65). These bones are 

 similar in all bonitos except for minor variations. 

 Postcleithrum 2 of Gymnosarda has an elongate 

 upper end and a curved lower portion. The broad 

 process of postcleithrum 2 is much enlarged in 

 Allothunnus as in Thunnus. 



PELVIC GIRDLE 



The pelvic fin rays (I, 5) attach directly to the 

 paired basipterygia which make up the pelvic 

 girdle. The bones are fused together along the 

 midline and are imbedded in the ventral ab- 

 dominal wall free from connections with any other 

 bones. Each basipterygium is composed of three 



main parts (Figure 66): a wide anterodorsal plate 

 and two processes: an anterior process (anterior 

 xiphoid process of de Sylva 1955) and a shorter, 

 stronger, posteriorly directed styliform process 

 (posterior xiphoid process of de Sylva 1955). There 

 are three wings to the anterodorsal plate 

 (Kishinouye 1923): external, internal, and vertical 

 (ventral). Anteriorly, the external wing turns into 

 the same vertical plane and merges into the ver- 

 tical wing. The internal wing and the external 

 wing meet in one plane posteriorly along a ridge. 

 A "valleylike" depression is present in the 

 posterior half of the anterodorsal plate in all the 

 bonitos except Allothunnus (Figure 66f). The in- 

 ternal wing of Allothunnus attaches to the ver- 

 tical wing horizontally at a right angle which is 

 completely separate from the external wing, as in 

 Thunnus (de Sylva 1955, figs. 50-52). The vertical 

 wing is the largest and most variable character of 

 the bonito basipterygium. The vertical wings of 

 Orcynopsis, Cybiosarda, and Sarda are elongate 

 and have pointed anterior ends. Gymnosarda and 

 Allothun7ius have vertical wings that are shorter 



588 



