FISHERY BULLETIN; VOL 78. NO. 4 



and Counts 1955), some of the anterior caudal 

 rays, both dorsally and ventrally, articulate with 

 unmodified neural and haemal spines; other rays 

 lie between the spines with no basal supports 

 (Figure 3). 



A symmetrical fin fold surrounds the tip of the 

 notochord in specimens 3.1-5.5 mm SL (Figure 3). 

 In 7.5 mm SL larvae, mesenchymal thickenings 

 occur dorsal and ventral to the notochord. By 7.8 

 mm SL, the ventral thickening is differentiated 

 into three cartilaginous plates constituting 

 hypurals 1, 2, and 3 anteriorly, and hypurals 4-6 

 posteriorly (Figure 3B). In 9.5 mm SL specimens 

 fin rays are considerably increased in number 

 ( Figure 3C). In 10.5 mm SL specimens the urostyle 

 begins to flex, and the unossified hypurals 1, 2-3, 

 and 4-6, as well as epurals 1 and 2 are differen- 

 tiated (Figure 3D). Ossification proceeds rapidly 

 during notochord flexion from anterior to posterior 

 regions of the caudal complex. By 11.9 mm SL 

 (Figure 3E), all preural centra are ossified, and all 

 hypurals and both epurals have begun ossifying. 

 Caudal fin rays have begun ossifying, beginning 

 ventrally in the region of the inferior hypurals. 



By 15.0 mm SL, all centra except the postural 

 centrum are ossified; the hypurals and epurals are 

 incompletely ossified (Figure 3F). Rays continue 



ossifying, proceeding posteriorly on the ventral 

 margin and on the superior hypural and pro- 

 gressing anteriorly from epural number 2. By 19.4 

 mm SL all caudal rays posterior to preural cen- 

 trum 12 are ossified. By 25.0 mm, the caudal fin is 

 completely ossified (Figure 3G) and resembles in 

 all details that of a 41.1 mm SL juvenile (Figure 

 3H). 



We were unable to detect fusion of hypurals in 

 the caudal fin of M. proximus during ontogeny. In 

 the smallest larvae in which we could detect de- 

 velopment of hypural elements (7.8-8.1 mm SL), 

 only three hypurals could be observed. We believe, 

 however, that these hypurals represent 1) an an- 

 terior, inferior hypural 1 (parhypural); 2) an in- 

 ferior hypural representing a fusion of hypurals 2 

 and 3; and 3) a superior hypural representing a 

 fusion of hypurals 4-6. This reasoning is predi- 

 cated on 1) it is generally accepted that the 

 evolutionary trend in fishes is toward a reduction 

 in the number of hypurals, presumably by fusion 

 of the constituent elements (Gosline 1961; Rosen 

 and Patterson 1969; Marshall and Cohen 1973); 2) 

 members of the family Moridae, generally consid- 

 ered a more primitive family than Gadidae 

 (Svetovidov 1948; Greenwood et al. 1966; Rosen 

 and Patterson 1969), possess three inferior and 



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