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Sturgeons of the Genus Scaphirhynehus 173 <br />backward- projecting serrations (present in Pseudoscaphirhynchus kauf- <br />x <br />manni; condition unknown to us in other species). Retrorse spines <br />near end of snout Ranting (P. fedtschenkoi), absent or poorly developed <br />(P. hermm:ni), or few (3 to 7) and long and strong (P. kaufmanni). <br />? <br />Caudal filament rather heavy and whiplike, or absent. Basin of the Aral <br />Sea, Siberia: drainages of the Amu Darya and the Syr Darya. not found <br />in the Aral Sea itself. Three species ............... Pseudoscanhirhync•hus <br />3b. Caudal peduncle completely armored, notably depressed, and loi;.- -tip of <br />anal fin remote from caudal base; caudal - peduncle length 15 to 36 per <br />cent of standard length. Barbels fringed. Gill openings with their <br />loner ends only narrowly separated. Pectoral spine well developed but <br />not notably stout. Clavicles not keeled. Retrorse spines near end of <br />snout numerous, short and slender (obliterated with growth). Caudal <br />filament slender, short in adults. United States: basins of the <br />sippi Rirer and the Rio Grande. Two species........... Sc•aj:;.ir.,jnchus <br />In the striking elongation and armature of the caudal peduncle, <br />surely interpretable as specializations, Scaphirltynchus is unique <br />among living sturgeons. That these features are not of recent ac- <br />quisition is evident from their presence in a shovelnose sturgeon from <br />the Upper Cretaceous, twenty -four miles southea,' <br />_Montana, that was referred to by Mac3lpin (1947: 16b). This <br />- :,, oimen, Museum of Paleontology-, University of - -Michigan, No, <br />_-_ :10, has been studied by Norman J. Wilimovsky-, who will soon <br />report on it. Thus Scaphirhynchus (or its ancestral stock) had as- <br />sumed its most distinctive structural features b,, t1a Cieta,.cous. <br />The zoogeographic pattern of the Scaphirhy-nchinae may well have <br />been established by that time, since the more highly modified group <br />+,- n occurred in an area within the present range of Scaphirhynchtis. <br />THE GE--,-us SCAPHIR.HY\ CHUS <br />In establishing the name Parascaphirhynchus albus, Forbes and <br />Richardson (1905: 38) commented: "Recognizing, as we are disposed <br />to do, the generic criteria proposed for the scaphirhy-nchoids by Berg <br />('0.1), we regard this form as generically distinct from species hitherto <br />c1. - cribed." They forthwith proposed Parascaphirhynchus as a new <br />gcuus. Berg (1911: 138, 308 -309, and 1948: 104), however, did not <br />support this decision, and placed albus in Scaphirhynchus,'- an action <br />s Since Scaphirhynch:cs is neuter, the adjectival specific name should properly be <br />written album, as pointed out by Hubbs (1951: 1.1) and by Riggs and'Nloore (1951). <br />We regard platorynchus as a substantive and therefore do not place it in agreement <br />«iti; the generic name. <br />L °yd <br />