The gross anatomy of the Gadoid Fish, Urophycis tenuis (Mitchill) 1815, with emphasis on its osteology

The systematics of the Gadidae is reviewed. Previous references to Urophycis are given. The general biology of Urophycis tenuis is presented. Definitions and synonyms of the teleost skeletal elements are listed. -- External characters, internal morphology, suid osteology of U. tenuis are described from 17 specimens from Holyrood Pond, St. Mary's Bay, Newfoundland. Viscera, skull, vertebral column and ribs, girdles, and fins are figured. -- The upper jaw is longer than the lower jaw and reaches as far back as the rear edge of the orbit. Along the lateral line there are 135 to 139 cycloid scales. -- The intestine is relatively long and heavily coiled. The physoclistous swimbladder is well-developed and related to the anterior vertebrae. -- The well-formed rostral cartilage performs as a key element in the antorbital portion of the skull. The fused frontals are the largest bones in the cranium. The opisthotics are large and bear moderately sized processes. There are 4 complete branchial arches but only 2 weak basibranchials. The 3rd pair of epibranchials are toothed. The posttemporal and supracleithrum are very weakly developed. -- The vertebral column is composed of 49 to 51 amphicoelous vertebrae. The 3rd and 4th vertebrae are modified to associate with the anterior end of the swimbladder. Parapophyses and ribs are borne by the 3rd and 4th vertebrae and all of the abdominal vertebrae except the last 2. A haemal funnel is formed by the first few anterior caudal vertebrae. Two hypurals, 1 epurals, 2 dorsal radials, and 2 ventral radials are associated with the last 3 vertebrae and support a number of caudal fin rays. The ultimate is of gadoid type. The spinal nerves leave the neural canal via open grooves between the bases of the neural arches and the postzygapophyses. Vertebral abnormalities occur on certain vertebrae in one specimen and are described