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Twelve strains of serotype III group B streptococci (8 isolated from cases of neonatal disease, 3 isolated from asymptomatically colonized infants, and 1 laboratory reference strain) were examined for in vitro production of three potential extracellular virulence products: type-specific antigen, neuraminidase, and protease. In addition, virulence in a mouse model, expressed as 50% lethal dose, was determined for the 12 strains to determine whether a relationship existed between the production of any of the three extracellular products and virulence. Only production of extracellular type-specific antigen showed a correlation with virulence in the mouse model. The high producers of extracellular type-specific antigen were an average of 166-fold more virulent for mice than low producers of the same component. There was no correlation between virulence and either neuraminidase or protease production, nor was there a correlation between either of these two extracellular products and the levels of extracellular type-specific antigen. When levels of group B streptococci of each type (a high and low producer of extracellular type-specific antigen) in organs of infected mice were examined, comparable levels of organisms were found in the brain, spleen, and lungs of mice near death regardless of the initial inoculum. However, the high producer of extracellular type-specific antigen caused death in mice with a 2 to 3 log lower inoculum than the low producer, suggesting that these strains may be more invasive.

Pico formation-________________________ 321 Saugus formation,______________________ Quaternary system____________________________ Pleistocene series.__________________________ Terrace deposits._______________________ 322 Alluvium. _____________________________ 323 Turbidity current features in the Tertiary rocks__._ 323 Nature of turbidity currents.__-_______-_-__ 323 Interrupted gradations-_____________________ 325 Angular fragments in sandstone._____________ 325 Irregular contacts_________________________ 326 Intraformational breccias.___________________ 327 Current marks____________________________ 330 Slump structures and convolute bedding. ______ 332 Structure-__________________________________ 334 Regional relations_____________________________ 334 Structural history_____________________________ 334 PreLate Cretaceous_______________________ T34 Late Cretaceous and early Tertiary.____-_.___ F34 Early and middle Miocene.__________________ ?35 Late Miocene.

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The Pancho Rico Formation of Pliocene age comprises sandy marine strata and interbedded finer grainr.d rocks. It generally overlies the marine Monterey Shale of Miocene age and underlies the nonmarine Paso Robles Formation of Pliocene and fleistocene(?) age in southern Monterey County, Calif. Loally it lies on the basement complex or on the Santa Margalita Formation of upper Miocene age. It crops otrt from north of King City southeastward for more than 50 miles to beyond the Nacimiento River and Vineyard Canyon. The Pancho Rico contains sandstone, mudstone, porcelaneous mudstone, porcelanite, diatomaceous mudstone, and conglomerate. Where the Pancho Rico overlies the Monterey Shale, its lower contact is at the base of the stratigraphically lowest sandstone unit above the typically finer grained Monterey. •where the Pancho Rico overlies the Santa Margarita Formation, its lower contact is at the top of the stratigraphically highest bed that contains Ostrea titan, a giant oyster characteristic of the Santa Margarita. The upper contact of the Pancho Rico is at the top of the stratigraphically highest lithologic unit that contains marine fossils. Both the upper and lower contacts are conformable and gradational. At some localities the unit probably intertongues with the Paso Robles Formation, and at others, with the Monterey Shale. The thickness of the Pancho Rico ranges from less than 20 feet to more than1,000 feet. The molluscan fauna of the Pancho Rico Formation consists principally of species not previously reported from the Salinas Valley area. Among the 141 larger invertebrate taxa recorded in this paper are many species indicative of Pliocene age, as that epoch is recognized in the Pacific Coast megafossil chronology. Faunal correlation is made with the type Jacalitos)!'ormation-exposed near Coalinga-a biostratigraphic unit that has been traditionally regarded as the standard for the lower Pliocene of the Pacific Coast. The molluscan fauna of the Pancho Rico implies a shallowwater marine environment considerably warmer than exists today at comparable latitudes and similar to that off the west coast of Baja California, Mexico. The wide distribution of several warm-water indicators in the early Pliocene of the Salinas Valley area and the absence of these indicators from contemporaneous strata to the north and northwest suggest that a Pliocene seaway connected the Salinas Valley area to the Santa Maria basin to the south. Local moderate-depth assemblages in exposures of the Pancho Rico Formation in the northwestern part of the area are of a northern, cool-water type and may indicate interchange with Pliocene faunas to the north through a northwest-trending marine trough. ACKNOWLEDGMENTS E. J. Moore studied eolleetions of fossil mollusks from 18 localities (see list of fossil loes., M902-M1067) in 1960 and 1961. These collections were rexamined and additional fossils were colleeted during preparation of this paper. Most of the echinoid identifications were made by J. Wyatt Durham. C. L. Rice made the initial collec...