FEENEY: EGGS AND LARVAE OF YELLOWCHIN SCULPIN 



Ossification 



Ossification begins in larvae at least 5.3 mm NL 

 long. The cleithrum, premaxilla, maxilla, mandible, 

 parts of the neurocranium, and 3 of 6 branchiostegal 

 rays on each side are ossified. The first 14 verte- 

 brae, the middle 10 out of 12 principal caudal rays, 

 11-13 pectoral rays, 2-3 preopercular spines, and 

 opercle bone, and all of the branchiostegal rays 

 become ossified at 6.8-7.0 mm. 



Ossification is well developed in specimens 7.4 mm 

 FL long or greater. The nasal, quadrate, dorsal 

 spines, and the first 28 of 33 vertebrae become ossi- 

 fied as well as the hypural plates and all of the prin- 

 cipal caudal rays. 



A double row of teeth appears on the lower jaw 

 of double-stained larvae between 6.8 and 7.4 mm FL 

 in length. On the upper jaw a single row of teeth 

 is seen in larvae 8.5 mm SL or greater in length. 



Spination 



One to three preopercular spines appear at 6.5-7.0 

 mm FL. Four preopercular spines are visible in lar- 

 vae over 7.0 mm FL. Nasal and parietal spines form 

 at 9.0-9.3 mm SL. Double-stained material shows 

 the parietal spine arising from two arcs of bone that 

 fuse distally into one spine before breaking the sur- 

 face of the skin. A foramen remains in the center 

 of the spine and is retained in the parietal spines 

 of juveniles and adults. 



Development of the Caudal Complex 



The caudal fin anlage begins to form in preflex- 

 ion larvae of about 5.3 mm NL (Fig. 4A). During 

 flexion three non-ossified hypural elements form 

 ventral to the notochord (Fig. 4B). The first hypural 

 (identified as HY1.3) may be a remnant of a fusion 

 process of two to three elements. Matarese and 

 Marliave (1982) described three elements that fuse 

 to form the inferior hypural plate in Ascelichthys 

 rhodorus; a foramen is left where the parhypural 

 (counted as HYj) fuses with HY2 and HYg. In I. 

 quadriseriatus a foramen is present in HY^.g. 



The second and third hypural elements (HY4 and 

 HY5) form separately (Fig. 4B-C) and fuse to form 

 the ossified superior hypural plate (HY4.5) (Fig. 

 4D). Finally, the two plates (HYj.g and HY4.5) begin 

 to fuse anteriorly in juveniles (Fig. 4D). 



Cartilaginous neural spines begin to form during 

 flexion (Fig. 4B). By about 8.7 mm SL the neural 

 spine on the first preural centrum (PUi) appears 

 (on one specimen) as two distinct elements (Fig. 4C). 



B 



HS HY1.3 



C P"; 



D 



Figure 4.— Caudal complex of Jceliniis quadriseriatus: A) 5.3 

 mm (LACM 012-88-36-BB-Ol); B) 6.8 mm (LACM 012-88-36- 

 BB-01); C) 8.7 mm (LACM 012-88-36-BB-Ol); D) 27.8 mm 

 (LACM 43579-1). EP = epural; HS = hemal spine; HY = 

 hypural; NC = notochord; NS = neural spine; PU = preural cen- 

 tra; U = urostyle; UN = uroneural. 



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