. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. Marine Hatchetfishes • Baird 9 ized by a modification of the first neural spine into a short triangulate, vertical blade. The second neural spine often sup- ports the first. In marked contrast, the gonostomatid genera examined (also Vin- ciguerria, see Weitzman, 1967b) show little modification in this area, and the first neural spine is elongate and forms an integral part of the upper caudal lobe. Stemoptyx shows a high degree of special- ization with considerable reduction or fusion of elements. Fohjipnus shares with
. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. Marine Hatchetfishes • Baird 9 ized by a modification of the first neural spine into a short triangulate, vertical blade. The second neural spine often sup- ports the first. In marked contrast, the gonostomatid genera examined (also Vin- ciguerria, see Weitzman, 1967b) show little modification in this area, and the first neural spine is elongate and forms an integral part of the upper caudal lobe. Stemoptyx shows a high degree of special- ization with considerable reduction or fusion of elements. Fohjipnus shares with MaiiroVicus (and Vinciguenia) the lack of fusion in hypurals 5 and 6. In some respects Fohjipnus resembles the gonostomatid gen- era examined in size and shape of the uroneurals although, in general, it appears similar to Argijropeleciis. Axial skeleton (Figs. 8-11). While there is a similarity in structure and appearance of the vertebral centra in all genera ex- amined, there are differences in neural and haemal spine pattern and structure. Pos- teriorly, the haemal and neural spine ar- rangement is symmetrical in all cases. In Maiirolictis and Valenciennellus both spines are relatively long, unflattened, and ta]:)ering. The sternoptychid genera show a definite broadened and flattened con- dition particularly evident at the distal end. FoJijipnus and Argijropeleciis are alike in this respect. Stemoptyx, with considerable elongation of the posterior neural and haemal spines, reflects an independent and highly modified condition. Vincigucrria (Ahlstrom and Counts, 1958) appears more similar to Fohjipnus than either of the gonostomatids examined. Anteriorly, the symmetrical pattern of haemal and neural spines continues in Valenciennellus with no marked transi- tional region. However, in Maurolicus and the Sternoptychidae, there is an area of transitional vertebrae which is peculiar. There is a reduced, although fully formed, plural rib-bearing member followed by a number of ch
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