Memoirs of the Museum of Comparative Zoölogy, at Harvard College, Cambridge, Mass . iffer-ences between the two groups, which aiipear especially, among others, in tiie jaws, the branchial skeleton,the .shoulder girdle and the pectoral fins. Tlie girdle of tlic shark, fig. 1, is remotely attached to thevertebrae in its scapulary extensions; it is considerably arclied and the fins are placed rather behind itstransverse axis. In the ray, fig. 2, the girdle is firmly and superiorly attached to the vertebrae by meansof a scapular element and the fins are lateral and forward of the articulations as
Memoirs of the Museum of Comparative Zoölogy, at Harvard College, Cambridge, Mass . iffer-ences between the two groups, which aiipear especially, among others, in tiie jaws, the branchial skeleton,the .shoulder girdle and the pectoral fins. Tlie girdle of tlic shark, fig. 1, is remotely attached to thevertebrae in its scapulary extensions; it is considerably arclied and the fins are placed rather behind itstransverse axis. In the ray, fig. 2, the girdle is firmly and superiorly attached to the vertebrae by meansof a scapular element and the fins are lateral and forward of the articulations as well as behind copula, hhij, is divided into sections, segmentetl, and dist inct from the cartilages behind it; in the rayit is unsegmented and is attached to the ceratohyals, chij {ehy in Plate). Strong cartilages appear in thegill covers of the ray, sp. The postbranchial stay, jd&.s, has its greatest development in Pristis and, asshown in the following plates, dwindles in approaching the rays of highest rank. Mem. Mus. Comp. Zool., Vol. 36. Plagiostomes. Plate E. N. FISCHER, DEL HELIOTVPE CO PLATE 66. PLATE 65. RHINOBATIDAE. Fig. 1. DjiDDENSis. M. C. Z. .806 (Page 268). Fig. 2. Rhinobatus pehcel-LENS. M. C. Z. 435 (Page 278). Fig. 3. Syrrhina (Page 285). The skeleton of the Rhinobatidae is closely allied to that of the Pristidae. The copula, hbr 1, isunsegmeiited, the other basibranchials are broadened fused and contorted, the antorbital, ao, is extendedfarther outward from the skull and the shoulder girdle is much widened. The basibranchials arc sketchedfrom young individuals and must of course differ considerably from those of larger or adult sijecimens.
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectzoology, bookyear1913
