Tectus

Abstract: Richly fossiliferous Middle Cretaceous sediments occur on the Pacific coast of Baja California, Mexico. Sediments of this age are represented by a 160 meter thick section of the Alisitos formation exposed at Punta China, approximately 120 kilometers south of the United States boundary. There two lithologically distinct members can be recognized: an upper member composed principally of biohermal limestones with interbedded coarsely pyroclastic sediments, and a lower member composed almost entirely of fine sediments. The Punta China section is unconformably overlain by late Upper Cretaceous and Quaternary deposits. The fauna of the Alisitos formation at Punta China is characterized by caprinid pelecypods, corals, and cerithiid and nerineid gastropods. Fifty-four species and varieties of the Gastropoda, 28 of them new, are described in detail and figured. Tentatively identified and listed are 73 species representing the more prominent pelecypods, brachiopods, bryozoans, corals, echinoderms, ostracodes, and Foraminifera. In contrast to provincial Middle Cretaceous faunas further north, the Punta China fauna includes cosmopolitan elements. The gastropods Tectus (Tectus) texanus (Roemer), Turritella (Haustator) aff. T. (H.) seriatim-granulata Roemer, Semineritina apparata (Cragin), Pyrazus (Echinobathra) austinense (Roemer), Tylostoma (Tylostoma) mutabilis Gabb, Liocarenus (Liocarenus) formosum (Cragin), and Actaeonella parvus (Stanton) occur in Texas and adjacent parts of Central America and the Caribbean, indicating marine communication with the Pacific during Middle Cretaceous times. Otostoma (Lyosoma) japonica (Nagao), Cimolithium miyakoense (Nagao), Natica importuna Nagao, and Natica japonica (Nagao) are Japanese species. Microschiza (Cloughtonia) scalaris (Conrad) and Actaeonella fusiformis Coquand occur in the Mediterranean region. Recognition of the Foraminifera Orbitolina texana (Roemer) in the Alisitos formation provides the first record of this widely distributed species on the West Coast of North America. Faunal studies thus far completed suggest a middle Albian age for at least the upper member of the Punta China section of the Alisitos formation. The environmentally and faunally distinct lower member may represent a similar age or may be as old as Aptian. New species and varieties described are: Agnathodonta brooksi, Anchura (Anchura) andersoni, A. (Perissoptera) hannai, Angaria (Angaria) gwynae, Cassiope (Cassiope) kleinpelli, C. (Gymnentome) gwynae, Cerithiopsis stantoni, Cerithium? emersoni, Cimolithium eleanorae, C. miyakoense (Nagao) var. tomdsensis, Cirsochilus gilberti, Encycloscala emersoni, Euthriofusus wenzi, Keilostoma quaidei, Mesalia (Mesalia) mauryae, Nerinea (Plesioptygmatis) bdsei, N. (P.) tomdsensis, Neritoma (Neridomus) woodfordi, N. (N.) delpeyae, Oligoptycha? popenoei, Pseudonerinea stantoni, P. stirtoni, Pyrazus (Echinobathra) durhami, Pyrazus? harrissi, Tectus (Tectus) tomdsensis, Tectus? thalmanni, Turritella? durhami, Uchauxia beali, U. kirki.

Abstract: 1. In a long temperature gradient apparatus, Ptinus tectus aggregates around two distinct temperatures, 4 and 24° C. 2. In a circular temperature alternative chamber there is no marked avoidance of low temperatures if the gradient is steep, but characteristic avoiding reactions occur if the gradient is not very steep. 3. When the stationary animals are subjected to rising or falling temperatures in the long gradient, there is a well-marked evacuation temperature at 30-33° C., but none at lower temperatures. 4. A temperature preference around 24° C. is correlated with favourable temperature for growth and other activities. The aggregation around 4° C. is the result of a failure of coordinated behaviour in a particular kind of gradient, and P. tectus is practically immobilized by cold in that temperature region.

Abstract: Bornean Philautus are placed in ten species of four species-groups: the hosei-group includes hosei (Boulenger) and ingeri sp. n.; the vermiculatus-group, acutus sp. n. and kerangae sp. n.; the tectus-group, tectus sp. n.; the aurifasciatus-group, amoenus Smith, longicrus (Boulenger), mjobergi Smith, petersi (Boulenger) and umbra sp. n. The taxa acutirostris (Peters), longicrus, mjobergi and petersi are removed from the synonymy of aurifasciatus (Schlegel).

Abstract: Search for the origin of paralytic shellfish toxins occurring in coral reef crabs and gastropods resulted in a discovery of a calcareous red alga Jania sp. as the toxin progenitor. The alga was confirmed to contain gonyautoxins I, II and III, the first being the major component. The presence of this alga in the stomach of two toxic crabs Zosimus aeneus and Atergatis floridus and four gastropods Turbo marmorata, Turbo argyrostoma, Tectus pyramis and Tectus nilotica maxima evidenced that Jania sp. was the primary source of the toxins. Seasonal observation indicated that the toxin content in the alga reached the maximum in the spring.